NCERT Solutions For Class 8 Hindi Chapter 1 ध्वनि

प्रश्न-अभ्यास

Question 1. कवि को ऐसा विश्वास क्यों है कि उसका अंत अभी नहीं होगा?
Solution: कवि को ऐसा विश्वास इसलिए है क्योंकि अभी उसके मन में नया जोश व उमंग है। अभी उसे काफ़ी नवीन कार्य करने है। वह युवा पीढ़ी को आलस्य की दशा से उबारना चाहते हैं।

Question 2. फूलों को अनंत तक विकसित करने के लिए कवि कौन-कौन-सा प्रयास करता है?
Solution: फूलों को अनंत तक विकसित करने के लिए कवि उन्हें कलियों की स्थिति से निकालकर खिले फूल बनाना चाहता है। कवि का मानना है कि उसके जीवन में वसंत आया हुआ है। इसलिए वह कलियों को हाथों के वासंती स्पर्श से खिला देगा। वह फूलों की आँखों से आलस्य हटाकर उन्हें चुस्त व जागरूक करना चाहता है।

Question 3. कवि पुष्पों की तंद्रा और आलस्य दूर हटाने के लिए क्या करना चाहता है?
Solution: कवि पुष्पों की तंद्रा और आलस्य दूर हटाने के लिए उन पर अपना हाथ फेरकर उन्हें जगाना चाहता है। वह उनको चुस्त, प्राणवान, आभावान व पुष्पित करना चाहता है।
अतः कवि नींद में पड़े युवकों को प्रेरित करके उनमें नए उत्कर्ष के स्वप्न जगह देगा, उनका आलस्य दूर भगा देगा तथा उनमें नये उत्साह का संचार करना चाहता है।

Question 4. वसंत को ऋतुराज क्यों कहा जाता है? आपस में चर्चा कीजिए।
Solution: वसंत को ऋतुराज कहा जाता है क्योंकि यह सभी ऋतुओं का राजा है। इस ऋतु में प्रकृति पूरे यौवन होती है। इस ऋतु के आने पर सर्दी कम हो जाती है। मौसम सुहावना हो जाता है। इस समय पंचतत्व अपना प्रकोप छोड़कर सुहावने रूप में प्रकट होते हैं। पंचतत्व जल, वायु, धरती, आकाश और अग्नि सभी अपना मोहक रूप दिखाते हैं। पेड़ों में नए पत्ते आने लगते हैं। आम बौरों से लद जाते हैं और खेत सरसों के फूलों से भरे पीले दिखाई देते हैं। सरसों के पीले फूल ऋतुराज के आगमन की घोषणा करते हैं। खेतों में फूली हुई सरसों, पवन के झोंकों से हिलती, ऐसी दिखाई देती है, मानो, सामने सोने का सागर लहरा रहा हो। कोयल पंचम स्वर में गाती है और सभी को कुहू-कुहू की आवाज़ से मंत्रमुग्ध करती है। इस ऋतु में उसकी छठा देखते ही बनती है। इस ऋतु में कई प्रमुख त्यौहार मनाए जाते हैं, जैसे – वसंत पंचमी, महा शिवरात्रि, होली आदि।

Question 5. वसंत ऋतु में आनेवाले त्योहारों के विषय में जानकारी एकत्र कीजिए और किसी एक त्योहार पर निबंध लिखिए।
Solution: वसंत ऋतु में कई त्यौहार मनाए जाते है, जैसे – वसंत-पंचमी, महा शिवरात्रि, होली आदि।
होली
हमारा देश भारत विश्व का अकेला एवं ऐसा अनूठा देश है, जहँ पूरे साल कोर्इ न कोर्इ त्योहार मनाया जाता है। रंगों का त्योहार होली हिंदुओं का प्रसि़द्ध त्योहार है, जो फाल्गुन मास की पूर्णिमा को मनाया जाता है।
यह त्योहार रंग एवं उमंग का अनुपम त्योहार है जब वसंत अपने पूरे यौवन पर होता है। सर्दी को विदा देने और ग्रीष्म का स्वागत करने के लिए इसे मनाया जाता है। संस्कृत साहित्य में इस त्योहार को ‘मदनोत्सव’ के नाम से भी पुकारा जाता है।
होली के संबंध में एक पौराणिक कथा प्रचलित है कि भगवान विष्णु के परम भक्त प्रहलाद को अग्नि में जलाने के प्रयास में उसकी बुआ ‘होलिका’ अग्नि में जलकर स्वाहा हो गर्इ थी। इसी घटना को याद कर प्रतिवर्ष होलिका दहन किया जाता है। दूसरे दिन फाग खेला जाता है। इस दिन छोटे-बड़े, अमीर-गरीब आदि का भेदभाव मिट जाता है। सब एक दूसरे पर रंग फेंकते हैं, गुलाल लगाते हैं और गले मिलते हैं। चारों ओर आनंद, मस्ती और उल्लास का समाँ बँध जाता है। ढोल पर थिरकते, मजीरों की ताल पर झूमते, नाचते-गाते लोग आपसी भेदभाव भुलाकर अपने शत्रु को भी गले लगा लेते हैं। परन्तु कुछ लोग अशोभनीय व्यवहार कर इस त्योहार की पवित्रता को नष्ट कर देते हैं।
हमारा कर्तव्य है कि हम होली का त्योहार उसके आदर्शो के अनुरूप मनाएँ तथा आपसी वैमनस्य, वैर-भाव, घृणा आदि को जलाकर एक-दूसरे पर गुलाल लगाकर आपस में प्रेम, एकता और सद्भाव बढ़ाने का प्रयास करें।
“होली के अवसर पर आओ एक दूजे पर गुलाल लगाएँ
अपने सब भेदभाव भूलाकर, प्रेम और सद्भाव बढाएँ”

भाषा की बात

Question 1. ‘हरे-हरे’, ‘पुष्प-पुष्प’ में एक शब्द की एक ही अर्थ में पुनरावृत्ति हुई है।
कविता के ‘हरे-हरे ये पात’ वाक्यांश में ‘हरे-हरे’ शब्द युग्म पत्तों के लिए विशेषण के रूप में प्रयुक्त हुए हैं। यहाँ ‘पात’ शब्द बहुवचन में प्रयुक्त है।
ऐसा प्रयोग भी होता है जब कर्ता या विशेष्य एक वचन में हो और कर्म, या क्रिया या विशेषण बहुवचन में; जैसे – वह लंबी-चौड़ी बातें करने लगा।
कविता में एक ही शब्द का एक से अधिक अर्थों में भी प्रयोग होता है – ”तीन बेर खाती ते वे तीन बेर खाती है।” जो तीन बार खाती थी वह तीन बेर खाने लगी है।
एक शब्द ‘बेर’ का दो अर्थों में प्रयोग करने से वाक्य में चमत्कार आ गया। इसे यमक अलंकार कहा जाता है।
कभी-कभी उच्चारण की समानता से शब्दों की पुनरावृत्ति का आभास होता है जबकि दोनों दो प्रकार के शब्द होते हैं; जैसे – मन का/मनका।
ऐसे वाक्यों को एकत्र कीजिए जिनमें एक ही शब्द की पुनरावृत्ति हो।
ऐसे प्रयोगों को ध्यान से देखिए और निम्नलिखित पुनरावृत शब्दों का वाक्य में प्रयोग कीजिए –
बातों-बातों में, रह-रहकर, लाल-लाल, सुबह-सुबह, रातों-
रात, घड़ी-घड़ी।
Solution: बातों-बातों में – बातों-बातों में कब घर आ गया पता ही नहीं चला।
रह-रहकर – कल रात से रह-रहकर बारिश हो रही है।
लाल-लाल – लाल-लाल आँखों से पिताजी अमर को घूर रहें थे।
सुबह-सुबह – दादीजी सुबह-सुबह ही पूजा करने मंदिर निकल जाती हैं।
रातों-रात – ईश्वर की कृपा से रामन रातों-रात अमीर हो गया।
घड़ी-घड़ी – घड़ी-घड़ी शिक्षक उसे पढ़ाई में ध्यान लगाने के लिए टोकते रहते थे।

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NCERT Solutions for Class 8 Hindi Chapter 2 लाख की चूड़ियाँ

प्रश्न-अभ्यास

Question 1. बचपन में लेखक अपने मामा के गाँव चाव से क्यों जाता था और बदलू को ‘बदलू मामा’ न कहकर ‘बदलू काका’ क्यों कहता था?
Solution: बचपन में लेखक अपने मामा के गाँव चाव से इसलिए जाता था क्योंकि लेखक के मामा के गाँव में लाख की चूड़ियाँ बनाने वाला कारीगर बदलू रहता था। लेखक को बदलू काका से अत्यधिक लगाव था। वह लेखक को ढेर सारी लाख की रंग-बिरंगी गोलियाँ देता था इसलिए लेखक अपने मामा के गाँव चाव से जाता था।
गाँव के सभी लोग बदलू को ‘बदलू काका’ कहकर बुलाते थे इस कारण लेखक भी ‘बदलू मामा’ न कहकर ‘बदलू काका’ कहता था।

Question 2. वस्तु-विनिमय क्या है? विनिमय की प्रचलित पद्धति क्या है?
Solution: ‘वस्तु विनिमय’ में एक वस्तु को दूसरी वस्तु देकर लिया जाता था। वस्तु के लिए पैसे नहीं लिए जाते थे। वस्तु के बदले वस्तु ली-दी जाती थी। किन्तु अब मुद्रा के चलन के कारण वर्तमान परिवेश में वस्तु का लेन-देन मुद्रा के द्वारा होता है। विनिमय की प्रचलित पद्धति पैसा है।

Question 3. ‘मशीनी युग’ ने कितने हाथ काट दिए हैं।’ – इस पंक्ति में लेखक ने किस व्यथा की ओर संकेत किया है?
Solution: इस पांति में लेखक ने कारीगरों की व्यथा की ओर संकेत किया है कि मशीनों के आगमन के साथ कारीगरों के हाथ से काम-धंधा छिन गया। मानो उनके हाथ ही कट गए हों। उन कारीगरों का रोजगार इन पैतृक काम धन्धों से ही चलता था। उसके अलावा उन्होंने कभी कुछ नहीं सीखा था। वे पीढ़ी दर पीढ़ी अपनी इस कला को बढ़ाते चले आ रहे हैं और साथ में रोज़ी रोटी भी चला रहें हैं। परन्तु मशीनी युग ने जहाँ उनकी रोज़ी रोटी पर वार किया है। मशीनों ने लोगों को बेरोजगार बना दिया।

Question 4. बदलू के मन में ऐसी कौन-सी व्यथा थी, जो लेखक से छिपी न रह सकी?
Solution: बदलू लाख की चूड़ियाँ बेचा करता था परन्तु जैसे-जैसे काँच की चूडियों का प्रचलन बढ़ता गया उसका व्यवसाय ठप पड़ने लगा। अपने व्यवसाय की यह दुर्दशा बदलू को मन ही मन कचौटती थी। बदलू के मन में इस बात कि व्यथा थी कि मशीनी युग के प्रभावस्वरुप उस जैसे अनेक कारीगरों को बेरोजगारी और उपेक्षा का शिकार होना पड़ा है। अब लोग कारीगरी की कद्र न करके दिखावटी चमक पर अधिक ध्यान देते हैं। यह व्यथा लेखक से छिपी न रह सकी।

Question 5. मशीनी युग से बदलू के जीवन में क्या बदलाव आया?
Solution: मशीनी युग से बदलू के जीवन में यह बदलाव आया की बदलू का व्यवसाय बंद हो गया। वह बेरोजगार हो गया। काम न करने से उसका शरीर भी ढल गया, उसके हाथों-माथे पर नसें उभर आईं। अब वह बीमार रहने लगा।

Question 6. लाख की वस्तुओं का निर्माण भारत के किन-किन राज्यों में होता है? लाख से चूड़ियों के अतिरिक्त क्या-क्या चीज़ें बनती है? ज्ञात कीजिए।
Solution: लाख की वस्तुओं का निर्माण सर्वाधिक उत्तरप्रदेश में होता है। लाख से चूड़ियाँ, मूर्तियाँ, गोलियाँ तथा सजावट की वस्तुओं का निर्माण होता है।

भाषा की बात

Question 1. ‘बदलू को किसी बात से चिढ़ थी तो काँच की चूडि़यों से’ और बदलू स्वयं कहता है -” जो सुंदरता काँच की चूडि़यों में होती है लाख में कहाँ संभव है? ”ये पंक्तियाँ बदलू की दो प्रकार की मनोदशाओं को सामने लाती हैं। दूसरी पंक्ति में उसके मन की पीड़ा है। उसमें व्यंग्य भी है। हारे हुए मन से, या दुखी मन से अथवा व्यंग्य में बोले गए वाक्यों के अर्थ सामान्य नहीं होते। कुछ व्यंग्य वाक्यों को ध्यानपूर्वक समझकर एकत्र कीजिए और उनके भीतरी अर्थ की व्याख्या करके लिखिए।
Solution: व्यंग्य वाक्य – ‘अब पहले जैसी औलाद कहाँ?’
व्याख्या – आजकल किसी भी बुजुर्ग के मुख से आमतौर पर यह सुनने मिलता है जिसमें उनके हृदय में छिपा दुःख और व्यंग्य देखने मिलता है। उनका मानना है कि आजकल की संतान बुजुर्गों को अधिक सम्मान नहीं देती।

Question 2. ‘बदलू’ कहानी की दृष्टि से पात्र है और भाषा की बात (व्याकरण) की दृष्टि से संज्ञा है। किसी भी व्यक्ति, स्थान, वस्तु, विचार अथवा भाव को संज्ञा कहते हैं। संज्ञा को तीन भेदों में बाँटा गया है –
(क) व्यक्तिवाचक संज्ञा, जैसे – लला, रज्जो, आम, काँच, गाय इत्यादि
(ख) जातिवाचक संज्ञा, जैसे – चरित्र, स्वभाव, वजन, आकार आदि द्वारा जानी जाने वाली संज्ञा।
(ग) भाववाचक संज्ञा, जैसे – सुंदरता, नाजुक, प्रसन्नता इत्यादि जिसमें कोई व्यक्ति नहीं है और न आकार या वजन। परंतु उसका अनुभव होता है। पाठ से तीनों प्रकार की संज्ञाएँ चुनकर लिखिए।
Solution: (क) व्यक्तिवाचक संज्ञा – बदलू, बेलन, मचिया।
(ख) जातिवाचक संज्ञा – आदमी, मकान, शहर।
(ग) भाववाचक संज्ञा – स्वभाव, रूचि, व्यथा।

Question 3. गाँव की बोली में कई शब्दों के उच्चारण बदल जाते हैं। कहानी में बदलू वक्त (समय) को बखत, उम्र (वय/आयु) को उमर कहता है। इस तरह के अन्य शब्दों को खोजिए जिनके रूप में परिवर्तन हुआ हो, अर्थ में नहीं।
Solution:
इंसान – मनुष्य
रंज – दुख
गम – मायूसी
ज़िंदगी – जीवन
औलाद – संतान

The post NCERT Solutions for Class 8 Hindi Chapter 2 लाख की चूड़ियाँ appeared first on Learn CBSE.

NCERT Solutions for Class 8 Hindi Chapter 10 कामचोर

प्रश्न-अभ्यास

Question 1. कहानी में मोटे-मोटे किस काम के हैं? किन के बारे में और क्यों कहा गया?
Solution: कहानी में ‘मोटे-मोटे किस काम के हैं’ बच्चों के बारे में कहा गया है क्योंकि वे घर के कामकाज में जरा सी भी मदद नहीं करते थे तथा दिन भर उधम मचाते रहते थे। इस तरह से ये कामचोर हो गए थे।

Question 2. बच्चों के ऊधम मचाने के कारण घर की क्या दुर्दशा हुई?
Solution: बच्चों के उधम मचाने से घर अस्त-व्यस्त हो गया। मटके-सुराहियाँ इधर-उधर लुढक गए। घर के सारे बर्तन अस्त-व्यस्त हो गए। पशु-पक्षी इधर-उधर भागने लगे। घर में धूल, मिट्टी और कीचड़ का ढ़ेर लग गया। मटर की सब्जी बनने से पहले भेड़ें खा गईं। मुर्गे-मुर्गियों के कारण कपड़े गंदे हो गए। इस वजह से पारिवारिक शांति भी भंग हो गई। अम्मा ने तो घर छोड़ने का भी फैसला ले लिया।

Question 3. “या तो बच्चाराज कायम कर लो या मुझे ही रख लो।” अम्मा ने कब कहा? और इसका परिणाम क्या हुआ?
Solution: अम्मा ने बच्चों द्वारा किए गए घर के हालत को देखकर ऐसा कहा था। जब पिताजी ने बच्चों को घर के काम काज में हाथ बँटाने को कहा तब उन्होंने इसके विपरीत सारे घर को तहस-नहस कर दिया। जिससे अम्मा जी बहुत परेशान हो गई थीं। इसका परिणाम ये हुआ कि पिताजी ने घर की किसी भी चीज़ को बच्चों को हाथ ना लगाने कि हिदायत दे डाली। अगर किसी ने घर का काम किया तो उसे रात का खाना नहीं दिया जाएगा।

Question 4. ‘कामचोर’ कहानी क्या संदेश देती है?
Solution: यह एक हास्यप्रधान कहानी है। यह कहानी संदेश देती है की बच्चों को घर के कामों से अनभिज्ञ नहीं होना चाहिए। उन्हें उनके स्वभाव के अनुसार, उम्र और रूचि ध्यान में रखते हुए काम कराना चाहिए। जिससे बचपन से ही उनमें काम के प्रति लगन तथा रूचि उत्पन्न हो न कि ऊब।

Question 5. क्या बच्चों ने उचित निर्णय लिया कि अब चाहे कुछ भी हो जाए, हिलकर पानी भी नहीं पिएँगे।
Solution: बच्चों द्वारा लिया गया निर्णय उचित नहीं था क्योंकि स्वयं हिलकर पानी न पीने का निश्चय उन्हें और भी कामचोर बना देगा। वे कभी-भी कोई काम करना सीख ही नहीं पाएँगें। बच्चों को काम तो करना चाहिए पर समझदारी के साथ। बड़ों को उनको काम सिखाना चाहिए और आवश्यकता अनुसार मार्गदर्शन देना चाहिए।

Question 6. घर के सामान्य काम हों या अपना निजी काम, प्रत्येक व्यक्ति को अपनी क्षमता के अनुरूप उन्हें करना आवश्यक क्यों है?
Solution: अपनी क्षमता के अनुसार काम करना इसलिए जरूरी है क्योंकि क्षमता के अनुरूप किया गया कार्य सही और सुचारु रूप से होता है। यदि हम अपने घर का काम या अपना निजी काम, नहीं करेंगे तो हम कामचोर बन जाएँगे। हमें अपने कामों के लिए आत्मनिर्भर रहना चाहिए।

Question 7. भरा-पूरा परिवार कैसे सुखद बन सकता है और कैसे दुखद? कामचोर कहानी के आधार पर निर्णय कीजिए।
Solution: भरा-पूरा परिवार तब सुखद बन सकता है जब सब मिल-जुलकर कार्य करें व दुखद तब बनता है जब सब स्वार्थ भावना से कार्य करें। कामों के क्षमतानुसार विभाजित करने से कहानी जैसी दुखद स्थिति से बचा जा सकता है। कार्यों को बाँटने से किसी दूसरे को काम करने के लिए कहने की जरुरत होगी और तनाव भी उत्पन्न नहीं होगा।

Question 8. बड़े होते बच्चे किस प्रकार माता-पिता के सहयोगी हो सकते हैं और किस प्रकार भार? कामचोर कहानी के आधार पर अपने विचार व्यक्त कीजिए।
Solution: बडे होते बच्चे यदि माता-पिता को छोटे-मोटे कार्यों में मदद करें तो वे उनके सहयोगी हो सकते हैं जैसे अपना कार्य स्वयं, अपने-आप स्कूल के लिए तैयार हो जाएँ, अपने खाने के बर्तन यथा सम्भव स्थान पर रख आएँ, अपने कमरे को सहज कर रखें।
यदि हम बच्चों को उनका कार्य करने की सीख नहीं देते तो वह सहयोग के स्थान पर माता-पिता के लिए भार ही साबित होंगे। उनके बड़ा होने पर उनसे कोई कार्य कराया जाएगा तो वह उस कार्य को भली-भांति करने के स्थान पर तहस-नहस ही कर देंगे, जैसे की कामचोर लेख पर बच्चों ने सारे घर का हाल कर दिया था। इसलिए माता-पिता को बच्चों को उनके स्वभाव के अनुसार, उम्र और रूचि ध्यान में रखते हुए काम कराना चाहिए। जिससे बचपन से ही उनमें काम के प्रति लगन तथा रूचि उत्पन्न हो न कि ऊब। और उनके सहयोगी हो सके।

Question 9. ‘कामचोर’ कहानी एकल परिवार की कहानी है या संयुक्त परिवार की? इन दोनों तरह के परिवारों में क्या-क्या अंतर होते हैं?
Solution: कामचोर कहानी सयुंक्त परिवार की कहानी है इन दोनों में अन्तर इस प्रकार है –
एकल परिवार में सदस्यों की संख्या तीन से चार होती है – माँ, पिता व बच्चे होते है। सयुंक्त परिवार में सदस्यों की संख्या ज़्यादा होती है क्योंकि इसमें चाचा-चाची ताऊजी-ताईजी, माँ-पिताजी, बच्चे सभी सम्मिलित होते हैं। एकल परिवार में सारा कार्य स्वयं करना पड़ता है जबकि संयुक्त परिवार में सबलोग मिल-जुलकर कार्य करते हैं। एकल परिवार में जीवन के सुख-दुख का अकेले सामना करना पड़ता है जबकि सयुंक्त परिवार में सारे सदस्य मिलकर जीवन के सुख-दुख का सामना करते है।

भाषा की बात

Question 1. “धुली-बेधुली बालटी लेकर आठ हाथ चार थनों पर पिल पड़े।” धुली शब्द से पहले ‘बे’ लगाकर बेधुली बना है। जिसका अर्थ है ‘बिना धुली’ ‘बे’ एक उपसर्ग है।
‘बे’ उपसर्ग से बननेवाले कुछ और शब्द हैं –
बेतुका, बेईमान, बेघर, बेचैन, बेहोश आदि। आप भी नीचे लिखे उपसर्गों से बननेवाले शब्द खोजिए –
1. प्र ……………….
2. आ ……………….
3. भर ……………….
4. बद​ ……………….
Solution:
1. प्र – प्रबल, प्रभाव, प्रयोग, प्रचलन, प्रवचन
2. आ – आमरण, आभार, आजन्म, आगत
3. भर – भरपेट, भरपूर, भरमार, भरसक
4. बद – बदसूरत, बदमिज़ाज, बदनाम, बदतर

The post NCERT Solutions for Class 8 Hindi Chapter 10 कामचोर appeared first on Learn CBSE.

NCERT Solutions for Class 8 Hindi Chapter 18 टोपी

प्रश्न-अभ्यास

Question 1. गवरइया और गवरा के बीच किस बात पर बहस हुई और गवरइया को अपनी इच्छा पूरी करने का अवसर कैसे मिला?
Solution: गवरइया और गवरा के बीच आदमी के वस्त्र पहनने को लेकर बहस हुई। गवरइया वस्त्र पहनने के पक्ष में थी तथा गवरा विपक्ष में था। गवरइया को आदमी द्वारा रंग-बिरंगे कपड़े पहनना अच्छा लग रहा था जबकि गवरा का कहना था कि कपड़ा पहन लेने के बाद आदमी और बदसूरत लगने लगता है। कपड़े पहन लेने के बाद आदमी की कुदरती ख़ूबसूरती ढँक जाती है। उसी बहस के दौरान गवरइया ने अपनी टोपी पहनने की इच्छा को व्यक्त किया। उसकी इच्छा तब पूरी हुई जब एक दिन घूरे पर चुगते-चुगते उसे रुई का एक फाहा मिल गया।

Question 2. टोपी बनवाने के लिए गवरइया किस-किस के पास गई? टोपी बनने तक के एक-एक कार्य को लिखें।
Solution: टोपी बनवाने के लिए गवरइया धुनिया, कोरी, बुनकर और दर्जी के पास गई। धुनिया के पास रुई धुनवा कर वह उसे लेकर कोरी के पास जा पहुँची। उसे कोरी से कतवा लिया। कते सूत को लेकर वह बुनकर के पास गई उससे बुनकर से कपड़ा बुनवाया। कपड़े को लेकर वह दर्जी के पास गई। उसने उस कपड़े से गवरइया की टोपी सिल दी।

Question 3. गवरइया की टोपी पर दर्जी ने पाँच फुँदने क्यों जड़ दिए?
Solution: गवरइया की टोपी पर दर्जी ने पाँच फुँदने लगाए क्योंकि दर्जी को वाजिब मजदूरी मिली थी, जिससे वह खुश था। दर्जी राजा औए उसके सेवकों के कपड़े सिलता था जो उसे बेगार करवाते थे। लेकिन गवरइया ने अपनी टोपी सिलवाने के बदले में दर्जी को मजदूरी स्वरूप आधा कपड़ा दिया।

Question 4. गवरइया के स्वभाव से यह प्रमाणित होता है कि कार्य की सफलता के लिए उत्साह आवश्यक है। सफलता के लिए उत्साह की आवश्यकता क्यों पड़ती है, तर्क सहित लिखिए।
Solution: सफलता के लिए उत्साह आवश्यक है। कहा भी गया है कि मन के हारे हार है मन के जीते जीत। उत्साह से ही हमारे मन में किसी भी कार्य के प्रति जागरूकता उत्पन्न होती है। यदि हम किसी भी कार्य को बेमन से करेंगे तो निश्चय ही हमें उस कार्य में पूर्णतया सफलता नहीं मिलेगी।

Question 5. टोपी पहनकर गवरइया राजा को दिखाने क्यों पहुँची जबकि उसकी बहस गवरा से हुई और वह गवरा के मुँह से अपनी बड़ाई सुन चुकी थी। लेकिन राजा से उसकी कोई बहस हुई ही नहीं थी। फिर भी वह राजा को चुनौती देने को पहुँची। कारण का अनुमान लगाइए।
Solution: टोपी पहनकर गवरइया राजा को दिखाने पहुँची जबकि उसकी बहस गवरा से हुई और वह गवरा के मुँह से अपनी बड़ाई सुन चुकी थी। लेकिन राजा से उसकी कोई बहस हुई ही नहीं थी। फिर भी वह राजा को चुनौती देने को पहुँची क्योंकि गवरा ने बहस के दौरान कहा था कि टोपी मात्र राजा ही पहनता है। यह बात उसे अच्छी नहीं लगी थी।

Question 6. यदि राजा के राज्य के सभी कारीगर अपने-अपने श्रम का उचित मूल्य प्राप्त कर रहे होते तब गवरइया के साथ उन कारीगरों का व्यवहार कैसा होता?
Solution: यदि राजा के राज्य के सभी कारीगर अपने-अपने श्रम का उचित मूल्य प्राप्त कर रहे होते तब गवरइया के साथ उन कारीगरों का व्यवहार सामान्य होता और सर्वप्रथम वे राजा का काम करते क्योंकि उनका काम ज्यादा था।

Question 7. चारों कारीगर राजा के लिए काम कर रहे थे। एक रजाई बना रहा था। दूसरा अचकन के लिए सूत कात रहा था। तीसरा बागा बुन रहा था। चौथा राजा की सातवीं रानी की दसवीं संतान के लिए झब्बे सिल रहा था। उन चारों ने राजा का काम रोककर गवरइया का काम क्यों किया?
Solution: चारों ने राजा का काम रोककर गवरइया का काम किया क्योंकि उन लोगों को काम की वाजिब मजदूरी मिली थी, जिससे वे सब खुश थे।

भाषा की बात

Question 1. गाँव की बोली में कई शब्दों का उच्चारण अलग होता है। उनकी वर्तनी भी बदल जाती है। जैसे गवरइया गौरैया का ग्रामीण उच्चारण है। उच्चारण के अनुसार इस शब्द की वर्तनी लिखी गई है। फुँदना, फुलगेंदा का बदला हुआ रूप है।
कहानी में अनेक शब्द हैं जो ग्रामीण उच्चारण में लिखे गए हैं, जैसे – मुलुक-मुल्क, खमा-क्षमा, मजूरी-मजदूरी, मल्लार-मलार इत्यादि। आप क्षेत्रीय या गाँव की बोली में उपयोग होने वाले कुछ ऐसे शब्दों को खोजिए और उनका मूल रूप लिखिए, जैसे – टेम-टाइम, टेसन/टिसन-स्टेशन।
Solution:

Question 2. मुहावरों के प्रयोग से भाषा आकर्षक बनती है। मुहावरे वाक्य के अंग होकर प्रयुक्त होते हैं। इनका अक्षरश: अर्थ नहीं बल्कि लाक्षणिक अर्थ लिया जाता है। पाठ में अनेक मुहावरे आए हैं। टोपी को लेकर तीन मुहावरे हैं; जैसे – कितनों को टोपी पहनानी पड़ती है। शेष मुहावरों को खोजिए और उनका अर्थ ज्ञात करने का प्रयास कीजिए।
Solution:

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NCERT Solutions for Class 8 Hindi Chapter 14 अकबरी लोटा

प्रश्न-अभ्यास

Question 1:
“लाला ने लोटा ले लिया, बोले कुछ नहीं, अपनी पत्नी का अदब मानते थे।”
लाला झाऊलाल को बेढंगा लोटा बिलकुल पसंद नहीं था। फिर भी उन्होंने चुपचाप लोटा ले लिया। आपके विचार से वे चुप क्यों रहे? अपने विचार लिखिए।
Solution:
लाला झाऊलाल को बेढंगा लोटा बिलकुल पसंद नहीं था। फिर भी उन्होंने चुपचाप लोटा ले लिया क्योंकि वे अपनी पत्नी का अदब मानते थे। दूसरा वे पत्नी के तेज-तर्रार स्वभाव से भी अवगत थे उन्होंने सोचा कि अभी तो लोटे में पानी मिला है यदि चूँ कर दू तो कहीं बाल्टी में भोजन ना करना पड़े।

Question 2:
लाला झाऊलाल जी ने फौरन दो और दो जोड़कर स्थिति को समझ लिया।”
आपके विचार से लाला झाऊलाल ने कौन-कौन सी बातें समझ ली होंगी?
Solution:
दो और दो जोडकर स्थिति को समझना – अर्थात् परिस्थिति को भाँप जाना। लोटा गिरने पर गली में मचे शोर को सुनकर आँगन में एकत्र हो गई। एक अंग्रेज को भीगे हुए तथा पैर सहलाते हुए देखकर लाला समझ गए कि स्थिति गंभीर है और लोटा अंग्रेज को लगा है। इस समय उनका चुप रहना ही ठीक है।

Question 3:
अंग्रेज़ के सामने बिलवासी जी ने झाऊलाल को पहचानने तक से क्यों इनकार कर दिया था? आपके विचार से बिलवासी जी ऐसा अजीब व्यवहार क्यों कर रहे थे? स्पष्ट कीजिए।
Solution:
अंग्रेज़ के सामने बिलवासीजी ने झाऊलाल को पहचानने से इनकार कर दिया क्योंकि अंग्रेज़ का क्रोध शांत हो जाए और अंग्रेज़ को ज़रा भी संदेह न हो कि वह लाला झाऊलाल का आदमी है। तथा वह अपनी योजना पूरी करना चाहते थे जिससे पैसे की व्यवस्था हो सकें।

Question 4:
बिलवासी जी ने रुपयों का प्रबंध कहाँ से किया था? लिखिए।
Solution:
बिलवासीजी ने रुपयों का प्रबंध अपने ही घर से अपनी पत्नी के संदूक से चोरी कर किया था।

Question 5:
आपके विचार से अंग्रेज ने यह पुराना लोटा क्यों खरीद लिया? आपस में चर्चा करके वास्तविक कारण की खोज कीजिए और लिखिए।
Solution:
अंग्रेज़ को पुरानी ऐतिहासिक चीज़ें इकट्ठा करने का शौक था। ऐसा इसलिए कह सकते है क्योंकि दुकान से पुरानी पीतल की मूर्तियाँ खरीद रहा था। अंग्रेज़ ने बिलवासी के कहने पर लोटा, अकबरी लोटा समझकर 500 रूपए में खरीदा।

Question 6:
“इस भेद को मेरे सिवाए मेरा ईश्वर ही जानता है। आप उसी से पूछ लीजिए। मैं नहीं बताऊँगा।”
बिलवासी जी ने यह बात किससे और क्यों कही? लिखिए।
Solution:
‘बिलवासी’ जी ने यह बात ‘लाला झाऊलाल’ से कही क्योंकि बिलवासीजी ने रुपयों का प्रबंध अपने ही घर से अपनी पत्नी के संदूक से चोरी कर किया था इस रहस्य को वह ‘झाऊलाल’ के सामने खोलना नहीं चाहते थे।

Question 7:
“उस दिन रात्रि में बिलवासी जी को देर तक नींद नहीं आई।”
समस्या झाऊलाल की थी और नींद बिलवासी की उड़ी तो क्यों? लिखिए।
Solution:
झाऊलाल के लिए बिलवासीजी ने अपनी पत्नी के संदूक से पैसे चोरी किए थे अब वे अपनी पत्नी के सोने की प्रतीक्षा में थे ताकि वह पैसे चुप-चाप संदूक में रख दे। इसलिए समस्या झाऊलाल की थी और नींद बिलवासी की उडी थी।

Question 8:
लेकिन मुझे इसी जिंदगी में चाहिए।”
“अजी इसी सप्ताह में ले लेना।”
“सप्ताह से आपका तात्यर्य सात दिन से है या सात वर्ष से?”
झाऊलाल और उनकी पत्नी के बीच की इस बातचीत से क्या पता चलता है लिखिए।
Solution:
झाऊलाल और उनकी पत्नी के बीच की इस बातचीत से निम्न बातें उजागर होती हैं –

1. झाऊलाल की पत्नी को अपने पति झाऊलाल के वादे पर भरोसा नहीं था।
2. उनकी पत्नी ने पहले भी कुछ माँगा होगा परन्तु उन्होंने हाँ करने के बाद भी लाकर नहीं दिया होगा।
3. झाऊलाल कंजूस प्रवृत्ति के हैं।

Question 9:
क्या होता यदि
अंग्रेज़ लोटा न खरीदता?
Solution:
यदि अंग्रेज़ लोटा नहीं खरीदता तो बिलवासी जी को अपनी पत्नी से चुराए हुए रूपए लाला झाऊलाल को देने पड़ते। अन्यथा झाऊलाल अपनी पत्नी को पैसे नहीं दे पाते और अपनी पत्नी के सामने बेइज्जत होते।

Question 10:
क्या होता यदि
यदि अंग्रेज़ पुलिस को बुला लेता?
Solution:
यदि अंग्रेज़ पुलिस को बुला लेता तो सम्भवत: लाला झाऊलाल को गिरफ्तार कर लिया जाता या उन्हें जुर्माना देना पड़ता।

Question 11:
क्या होता यदि
जब बिलवासी अपनी पत्नी के गले से चाबी निकाल रहे थे, तभी उनकी पत्नी जाग जाती?
Solution:
गले से चाबी निकालते समय यदि बिलवासी जी की पत्नी जग जाती तो चोरी जैसा घिनौना काम करने पर उन्हें अपनी पत्नी के समक्ष शर्मिंदा होना पड़ता।

Question 12:
बिलवासी जी ने जिस तरीके से रुपयों का प्रबंध किया, वह सही था या गलत?
Solution:
बिलवासी जी ने जिस तरीके से रुपयों का प्रबंध किया, वह गलत था। अपनी स्वार्थ सिद्धि के लिए किसी को उल्लू नहीं बनाना चाहिए।

भाषा की बात

Question 1:
इस कहानी में लेखक ने जगह-जगह पर सीधी-सी बात कहने के बदले रोचक मुहावरों, उदाहरणों आदि के द्वारा कहकर अपनी बात को और अधिक मजेदार​/रोचक बना दिया है। कहानी से वे वाक्य चुनकर लिखिए जो आपको सबसे अधिक मजेदार लगे।
Solution:

1. अब तक बिलवासी जी को वे अपनी आँखो से खा चुके होते।
2. कुछ ऐसी गढ़न उस लोटे की थी कि उसका बाप डमरू, माँ चिलम रही हो।
3. ढ़ाई सौ रूपए तो एक साथ आँख सेंकने के लिए भी न मिलते हैं।

Question 2:
इस कहानी में लेखक ने अनेक मुहावरों का प्रयोग किया है। कहानी में से पाँच मुहावरे चुनकर उनका प्रयोग करते हुए वाक्य लिखिए।
Solution:

1. चैन की नींद सोना – (निश्चिंत सोना)
कुख्यात चोर के पकड़े जाने पर पुलिस चैन की नींद सोई।

2. आँखों से खा जाना – (क्रोधित होना)
परीक्षा में कम अंक आने पर माँ ने पुत्र को ऐसे देखा मानो आँखों से ही खा जाएगी।

3. आँख सेंकने के लिए भी न मिलना – (दुर्लभ होना)
हस्तकला से बनी वस्तुएँ तो आजकल आँख सेंकने के लिए भी नहीं मिलती हैं।

4. मारा-मारा फिरना – (ठोकरें खाना)
बेटे आलीशान घर में रहते है और बाप बेचारा मारा-मारा फिरता हैं।

5. डींगे सुनना – (झूठ-मूठ की तारीफ सुनना)
लाला जी घर में तो भीगी बिल्ली है परंतु बाहर अपनी बहादुरी की डींगें मारते फ़िरते हैं।

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The post NCERT Solutions for Class 8 Hindi Chapter 14 अकबरी लोटा appeared first on Learn CBSE.

NCERT Solutions for Class 8 Hindi Chapter 17 बाज और साँप

प्रश्न-अभ्यास

Question 1.
घायल होने के बाद भी बाज ने यह क्यों कहा, ”मुझे कोई शिकायत नहीं है।” विचार प्रकट कीजिए।
Solution:
घायल होने के बाद भी बाज ने यह कहा कि – “मुझे कोई शिकायत नहीं है।” उसने ऐसा इसलिए कहा क्योंकि वह किसी भी कीमत पर समझौतावादी जीवन शैली पसंद नहीं करता था। वह अपने अधिकारों के लिए लड़ने में विश्वास रखता था। उसने अपनी ज़िंदगी को भरपूर भोगा। वह असीम आकाश में जी भरकर उड़ान भर चुका था। जब तक उसके शरीर में ताकत रही तब तक ऐसा कोई सुख नहीं बचा जिसे उसने न भोगा हो। वह अपने जीवन से पूर्णतः संतुष्ट था।

Question 2.
बाज ज़िंदगी भर आकाश में ही उड़ता रहा फिर घायल होने के बाद भी वह उड़ना क्यों चाहता था?
Solution:
बाज ज़िंदगी भर आकाश में उड़ता रहा, उसने आकाश की असीम ऊँचाइयों को अपने पंखों से नापा। बाज साहसी था। वह किसी भी कीमत पर समझौतावादी जीवन शैली पसंद नहीं करता था। अतः कायर की मौत नहीं मरना चाहता था। वह अंतिम क्षण तक जीवन की आवश्यकताओं के लिए संघर्ष करना चाहता था।

Question 3.
साँप उड़ने की इच्छा को मूर्खतापूर्ण मानता था। फिर उसने उड़ने की कोशिश क्यों की?
Solution:
साँप उड़ने की इच्छा को मूर्खतापूर्ण मानता था क्योंकि वह मानता था कि वह उड़ने में सक्षम नहीं है। पर जब उसने बाज के मन में आकाश में उड़ने के लिए तड़प देखी तब साँप के मन में भी उत्सुकता जागी कि आकाश का मुक्त जीवन कैसा होता है ? इस रहस्य का पता लगाना ही चाहिए। तब उसने भी आकाश में एक बार उड़ने की कोशिश करने का निश्चय किया।

Question 4.
बाज के लिए लहरों ने गीत क्यों गाया था?
Solution:
बाज की बहादुरी पर प्रसन्न होकर लहरों ने गीत गाया था। उसने अपने प्राण गँवा दिए परन्तु ज़िंदगी के खतरे का सामना करने से पीछे नहीं हटा।

Question 5.
घायल बाज को देखकर साँप खुश क्यों हुआ होगा?
Solution:
साँप का शत्रु बाज है चूँकि वो उसका आहार होता है। घायल बाज उसे किसी प्रकार का आघात नहीं पहुँचा सकता था इसलिए घायल बाज को देखकर साँप के लिए खुश होना स्वाभाविक था।

Question 6.
कहानी में से वे पंक्तियाँ चुनकर लिखिए जिनसे स्वतंत्रता की प्रेरणा मिलती हो।
Solution:
कहानी की स्वतंत्रता से संबंधित पंक्तियाँ –

1. जब तक शरीर में ताकत रही, कोई सुख ऐसा नहीं बचा जिसे न भोगा हो। दूर-दूर तक उडानें भरी हैं, आकाश की असीम ऊँचाइयों को अपने पंखों से नाप आया हूँ।
2. “आह! काश, मैं सिर्फ एक बार आकाश में उड पाता।”
3. पर वह समय दूर नहीं है, जब तुम्हारे खून की एक-एक बूँद जिंदगी के अँधेरे में प्रकाश फैलाएगी और साहसी, बहादुर दिलों में स्वतंत्रता और प्रकाश के लिए प्रेम पैदा करेगी।

Question 7.
मानव ने भी हमेशा पक्षियों की तरह उड़ने की इच्छा की है। आज मनुष्य उड़ने की इच्छा किन साधनों से पूरी करता है।
Solution:
मानव ने आदिकाल से ही पक्षियों की तरह उड़ने की इच्छा मन में रखी है। किन्तु शारीरिक असमर्थता की वजह से उड़ नहीं पा रहा था जिसका परिणाम यह हुआ कि मनुष्य हवाई जहाज का आविष्कार कर दिखाया। आज मनुष्य अपने उड़ने की इच्छा की पूर्ति हवाई जहाज, हेलीकॉप्टर, गैस-बैलून आदि से करता है।

भाषा की बात

Question 1.
कहानी में से अपनी पसंद के पाँच मुहावरे चुनकर उनका वाक्यों में प्रयोग कीजिए।
Solution:

1. भाँप लेना – बच्चों का मुँह देखकर माता जी ने परीक्षा का क्या नतीजा आया होगा यह भाँप लिया।
2. हिम्मत बाँधना – मित्र के आने पर ही परीक्षा के लिए राहुल की हिम्मत बँधी।
3. अंतिम साँस गिनना – दादाजी की गिरती साँसें देखकर माता जी ने स्थिति भाँप ली वे कि वे उनकी अंतिम साँस गिन रहे हैं।
4. मन में आशा जागना – शिक्षिका की कहानी ने मेरे मन में आशा जगा दी।
5. प्राण हथेली में रखना – सिपाही ने देशवासियों की जान बचाने के लिए अपने प्राणों को हथेली में रख देते हैं।

Question 2.
‘आरामदेह’ शब्द में ‘देह’ प्रत्यय है। यहाँ ‘देह’ ‘देनेवाला’ के अर्थ में प्रयुक्त है। देनेवाला के अर्थ में ‘द’, ‘प्रद’, ‘दाता’, ‘दाई’ आदि का प्रयोग भी होता है, जैसे – सुखद, सुखदाता, सुखदाई, सुखप्रद। उपर्युक्त समानार्थी प्रत्ययों को लेकर दो-दो शब्द बनाइए।
Solution:
प्रत्यय       शब्द
द – सुखद, दुखद
दाता – परामर्शदाता, सुखदाता
दाई – सुखदाई, दुखदाई
देह – विश्रामदेह, लाभदेह, आरामदेह
प्रद – लाभप्रद, हानिप्रद, शिक्षाप्रद

The post NCERT Solutions for Class 8 Hindi Chapter 17 बाज और साँप appeared first on Learn CBSE.

NCERT Solutions for Class 10 Foundation of Information Technology – HTML (HyperText Markup Language)

Foundation of ITMathsScienceSocialEnglishHindiSanskritRD Sharma

Very Short Answer Type Questions [1 Mark each]

Question 1. HTML is a markup language. Expand the term HTML. CBSE 2002
Answer: HyperText Markup Language.

Question 2. Give examples of a container element in HTML. CBSE 2009
Answer: <HEAD>, <TITLE>, <BODY>.

Question 3. Give the examples of an empty element in HTML. CBSE 2010, 09
Answer: <BR>, <HR>

Question 4. Write the extension of HTML code file. CBSE 2005
Answer: .html or .htm

Question 5. What is the method of viewing the source code of the current page in the Web browser?
Answer: Right click on the Web page and then select View Source from the context menu.

Question 6. While writing HTML code, how do you find out how your Web page would look like? CBSE 2007
Answer: For this, open the HTML code file in a Web browser.

Question 7. Write HTML code to set the image ‘Pen. jpg’ stored in ‘My Pictures’ folder in C: as the background of your Web page. CBSE 2007
Answer: The HTML code is <BODY background=“C:\My Pictures \Pen.jpg”>.

Question 8. Identify the error(s) in the following HTML code. Also, write the correct code. CBSE 2008
<BODY color=“red” background =“school.j pg”>
Answer: The error in the code is that in place of color attribute there should be bgcolor.
The correct code is
<BODY bgcolor =“red” background =“school.jpg”>

Question 9. Write one basic difference between bgcolor and background attributes.
Answer: The bgcolor attribute is used for coloring the background of the document while background attribute specifies a background image for a document.

Question 10. Name two common graphic files formats that most browser recognise. CBSE 2007
Answer:  The two common graphic file formats are: .gif and .jpg.

Question 11. What is the use of width attribute in HTML? CBSE 2002
Answer: Width attribute specifies the width of a horizontal line in pixels or percent. Its default value is 100%.

Question 12. What do you understand by option alink used with <BODY> tag? CBSE 2010, 04
Answer: alink attribute defines the color of the link as it is being clicked on the Web page. The default color of alink is red.

Question 13. What do you understand by option vlink used with <BODY> tag? CBSE 2005, 04
Answer: vlink attribute defines the color of a link after it has been visited. The default color of vlink attribute is purple.

Question 14. Explain the following statement:
<BODY bgcolor=“yellow” text =“red” vlink=“blue”> AI2010
Answer: The code will set the Web page background color as yellow, text color as red and visited link color as blue.

Question 15. How the font size of a single line on a Web page be changed? CBSE 2005
Answer: The font size of a single line can be changed by using the following HTML code:

<FONT size =+1> This is a HTML text </FONT>.

Question 16. What is the use of <FONT> tag in HTML code? Write any two options used with this tag. CBSE 2002
Answer: The <FONT> tag is used to change the size, color and type face of the text on HTML page. It uses attributes such as size, face etc.

Question 17. Identify the errors and write the correct HTML code      CBSE 2011

1. <BODY background = ‘‘red”>
2. <FONT type =‘‘arial ”>

Answer:

1. <BODY bgcolor=“red”>
2. <FONT face=“arial”>

Question 18. Why do we insert comments in an HTML document, even though they are not displayed on a Web page? CBSE 2005
Answer: So, that user will be able to understand coding effects and meaning.

Question 19. What is the method of using comment line in the HTML code? CBSE 2005, 03
Answer: In HTML code, the comment line is declared as <!–Any text –>

Question 20. Which heading element gives the most prominent headings? CBSE 2007
Answer: <H1>

Question 21. Which tag is used to insert heading of third level on a Web page? CBSE 2007
Answer: <H3>

Question 22. What is the purpose of using the tags <H1>…<H6>? CBSE 2004
or
What is the method of using headings in HTML? CBSE 2004
or
Write the difference between <H1> and <H6> heading tags. CBSE2008
Answer: <HTML> provides six levels of headings. <H1> is the largest heading level while <H6> is the smallest heading level. These headings help us in obtaining a uniform look and feel for the document.

Question 23. How can anyone insert horizontal line in a Webpage? CBSE 2005
Answer: Using <HR> tag, anyone can insert horizontal line in a Web page.

Question 24. How would you display text in the title bar of a browser? CBSE 2005
Answer: To display text in a title bar of a browser, use the <TITLE> tag inside the <HEAD> tag in the HTML document.

 e.g.
 <HTML>
 <HEAD>
 <TITLE> HTML document </TITLE>
 </HEAD>
 </HTML>

Question 25. Explain the following statement:
<HR size=“5” align=”right” width=“60”> CBSE 2004
Answer: The given HTML code produces a horizontal rule with size 5, aligning right on page and of width 60.

Question 26. Write the HTML code to display horizontal line of red color. CBSE 2015
Answer: <HR color = “red”>

Question 27. Write the expansions of the following tags used in HTML. CBSE 2004

1. <BR>
2. <I>
3. <HR>
4. <U>

Answer:

1. <BR> — Break line
2. <I> — Italic
3. <HR> – Horizontal Rule
4. <U> — Underline

Question 28. Write the expansions of the following tags used in HTML. CBSE 2003

1. <A>
2. <!>

Answer:

1. <A> – Anchor tag
2. <!> – Comment tag

Question 29. Which HTML tag is used to insert an image in a page? Write an option used with this tag. CBSE 2002
Answer: The <IMG> tag is used to insert an image in a page. This tag uses the options like src, alt etc.

Question 30. What do you mean by src? CBSE 2007
Answer: The src is an attribute of <IMG> tag. It gives the URL of the image document.

Question 31. Write the full form of the following tags: CBSE 2008

1. <LI>
2. <IMG>

Answer:

1. <LI>-List item
2. <IMG>-Image

Question 32. What are the different forms of list used in HTML? Name any two. CBSE 2004
Answer: The different forms of list are ordered list and unordered list.

Question 33. What are two basic tags in HTML lists?
Answer: <OL> and <UL>

Question 34. What does a <LI> create when used in an unordered list?
Answer: <LI> creates bulleted points for each list item.

Question 35. Can you change the style of numbers in an ordered list?
Answer: Yes, we can change the style of numbers in an ordered list.

Question 36. Write the expansions of the following tags. CBSE 2002

1. <P>
2. <UL>
3. <OL>
4. <B>

Answer:

1. <P>-Paragraph
2. <UL>-Unordered list
3. <0>-Ordered list
4. <B >-Bold

Question 37. Find error(s) in the following HTML code segment. Rewrite the correct code. CBSE 2007
<UL style = square>
<LI> Water Bottles
<LI> Lunch Box
<LI> Handkerchief
</UL>
Answer: There should be type instead of style. So, correct line is <UL type =“square”>

Short Answer Type Questions [2 & 3 Marks each]

Question 1. What is the purpose of HTML? CBSE 2008
Answer: HTML (HyperText Markup Language) is used to create Web pages and tells the browser how to display them. It designs the basic layout and formatting of Web pages.
HTML is made up of elements or tags and attributes, which work together to identify document parts and tell browser how to display them.

Question 2. What is an attribute in HTML? CBSE 2007
Answer: HTML attribute is a modifier of HTML element. Attributes provide additional information about HTML elements. Attributes are always specified in rhe start tag of an element, after the element’s name. These come in name/value pairs like name=”value”.

Syntax

<TAG name = “val-ue”> (content to be modified by the tag) </TAG>

Where, TAG is the HTML element, name is the name of an attribute, set to the provided value.

Question 3. What is the purpose of using HTML tags and attributes for Web designing? CBSE 2013
Answer: HTML (HyperText Markup Language) is used to create Web pages. It designs the basic layout and formatting of Web pages by using tags and attributes.
The tag’s name tells the tag’s purpose and the attributes that follow the tag name give the additional information of the Web browser.

Question 4. Differentiate between container and empty elements used in HTML. CBSE 2011, 10, 02
or
Distinguish between container and empty tags. CBSE 2007
or
Sriram software solution has used different tags in its Website some are empty while majority are container. Give the detailed difference between container and empty elements. CBSE 2013
Answer:

Container elements HTML container elements require a starting as well as an ending tags.

e-g <HTML>, <HEAD>, <BODY>.

They affect the text appearing between their starting and ending tags.

Empty elements HTML empty elements require just a starting tag and not an ending tag.

e.g.
<IMG> , <BR> , <HR>.

They just carry out the job assigned to them.

Question 5. What is the <TITLE> tag? CBSE 2006
Answer: This tag defines the title of the document. Title must be a simple text and should not be same as the file name. It is placed between <HEAD> and </HEAD> tags.

Question 6. Find the error(s) in the following code and underline those errors.

<HTML>
<HEAD>
<TITLE> Example </HEAD>
</TITLE>
<B0DY> ........... </B0DY>
</HTML>

Answer:

</TITLE> should be placed before </HEAD>
The correct code is

<HTML>
<HEAD>
<TITLE> Example </TITLE>
</HEAD>
<B0DY> </B0DY>
</HTML>

Question 7. What is the use of <BODY> tag in HTML code? Write any two attributes used with this tag. CBSE 2010, 03
or
What does <BODY> tag in HTML contain? Write any two attributes used with this tag. CBSE 2008, 03
Answer: The <BODY> tag encloses the main part of the document. It contains all the contents of a document. Various markup elements are allowed within the body to indicate heading, paragraphs, lists, hypertext links, images and so on. The <BODY> tag uses various attributes such as background, bgcolor etc.

Question 8. Which tag do we use to change the size and style (face) of the text of an HTML file viewed on a Web browser? Also, explain any two attributes used with this tag. CBSE 2004
Answer: <FONT> tag is used to change the size and style (face) of the text of an HTML file displayed on a Web browser. Two attributes of <FONT> tag are as follows:

size: It specifies the size of the text inside a <FONT> tag.

Syntax

<F0NT size=“number”>

face: It specifies the font name of the text inside a <FONT> tag.

Syntax

<FONT face=“Font_family”>

Question 9. Write the HTML code to set the bgcolor as pink, heading level 2, text This is pink background’ as black and topmargin 60.
Answer:

<HTML>
<BODY bgcolor = "pink” topmargin=“60” text= “black”>
<H2>This is pink background</H2>
</BODY >
</HTML>

Question 10. List any two types of alignment that can be applied to a paragraph in HTML. CBSE 2008
Answer: Any two types of alignment that can be applied to a paragraph are as follows:

Left alignment: This type of alignment aligns text in left. This is the default alignment.

Syntax

<P align=“left”> </P>

Right alignment: This type of alignment aligns text in right within the paragraph.

Syntax

<P align=“right"> </P>

Question 11. Write the HTML code to create a paragraph whose text color is blue. CBSE 2015
Answer:

<P>
<FONT color=“blue”>
</FONT>
</P> or
</P style = “color : blue”>

Question 12. What is the function of <HR> tag in HTML? Give any two attributes used with it.
or
List any two attributes of <HR> tag. CBSE 2008, 09
Answer: <HR> tag is used to draw horizontal lines in the Web page. This horizontal line divides the screen horizontally. <HR> tag creates a shaded horizontal line between text. Attributes of <HR> tag are size, align and width.

Question 13. Difference between <BR> and <HR> tags.
Answer: <BR> tag is used to insert a line break which means the text/image following the tag will be moved to the next line while <HR> tag is used to insert horizontal line that can divide the information into sections.

Question 14. Explain the following with the help of an example: CBSE 2010

1. <U>……..</U>
2. <I>……..</I>

Answer:

1. <U>……..</U>. This element is used to underline the text.
   e.g. <U> School </U>
   Output
   School
2. <I>…….</I>. This element marks up text in italic form.
   e.g. <I> Hello </I>
   Output
   Hello

Question 15. How is <OL> tag different from <UL> tag? CBSE 2004
Answer: <OL> tag is used to indicate a list item as contained in an ordered or numbered form. <UL> tag is used to indicate a list item as contained in an unordered or bulleted form.

Question 16. What is the purpose of using type attribute used in lists? CBSE 2003
Answer: type attribute specifies the type of numbers or bullets depending on whether the list item is inside an ordered list or unordered list.

Question 17. What is the purpose of using start attribute used in lists? CBSE 2003
Answer: This attribute is used to change the beginning value of an ordered list. Normally, the ordered list begins with 1. It lets you further customise an HTML ordered list by setting a new starting digit for the ordered list element.

Syntax

<OL start=“value” type = “value”>

e.g.
<HTML> 
<HEAD>
<TITLE>
Ordered List with type attribute
</TITLE>
</HEAD>
<BODY>
<0L start=‘1" type=“1” >
<LI> Rose </LI>
<LI> Lotus </LI>
<LI> Lily </LI>
</OL>
</B0DY>
</HTML>

Output

1. Rose
2. Lotus
3. Lily

Question 18. What is the output of the following segment of the HTML code? CBSE 2010

<BODY>
<HR width=‘‘50%”>
<UL>
<LI> MANGO </LI>
<LI> APPLE </LI>
<LI> GRAPES </LI>
</UL> </BODY>

Answer: 

Output

• MANGO
• APPLE
• GRAPES

Question 19. Explain the following with the help of an example.
(a) <B>……..</B>
(b) <OL type =“1”>
Answer:
(a) <B> tag makes the text bold.
e.g. <B> This is a bold text </B>
Output
This is a bold text

(b) <OL> tag with attribute type of value “1” displays the lists of items with arabic numerals,

e.g.<OL type=“1”>
<LI> Mango </LI>
<LI> Apple </LI>
<LI> Banana </LI>
</OL>

Output
1. Mango 2. Apple 3. Banana

Question 20. What is the <OL>……..</OL> tag? Name any two attributes used with this tag. CBSE 2009
Answer:

<OL>………</OL> tag is used for the ordered list, i.e. a list of items to be displayed in a particular order. An ordered list is also a list of items. An ordered list starts with the <OL> tag. Each list item starts with the <LI> tag.

e.g.
<OL>
<LI> A </LI>
<LI> B </LI>
</OL>

Two attributes of <OL> tag are: start and type.

Question 21. What is definition list?
Answer: Definition List
This is a list of items, with a description of each item. HTML definition lists (<DL>) are indented list without any bullet symbol or any number in front of each item. This list elements have a unique array of tags and elements; the resulting lists are similar to those you would see in a dictionary.

Tags used in definition lists are as follows:

• <DL> Opening tag that detines the start of the list.
• <DT> List item that defines the definition term.
• <DD> Definition of the list item.
• </DL> Closing tag that defines the end of the list.

Question 22. Identify error(s) in the following HTML code. Also, write the correct code. CBSE 2008

<OL> type=“a” start=“d”>

Answer:

<OL> tag’s attributes should be placed in between <and>. In <OL> list, the start attribute must be set to a numeric value and type attribute specifies ‘A’, ‘a’, T ‘i’ or ‘1’. So, the correct code is

<OL type=“a” start="4”>

Question 23. Write a code to produce the following output.

Answer:

<HTML><BODY>
<DL><DT><B>Computer</B>
<DD>An electronic machine
<DT><B>CPU</B>
<DD> Brain of computer </DL> 
</BODY></HTML>

Long Answer Type Questions  [5 Marks each]

Question 1. What are the role of <HTML>……….</HTML> tags in HTML? CBSE 2009
The <HTML> and </HTML> tags are used to mark the beginning and end of the HTML document. The basic purpose of this tag is to make the browser and text editor identify that the document is an HTML document.This is a container element and does not affect the appearance of the document. The <HTML> element contains only the <HEAD> and <BODY> elements, which in turn contains a number of other elements.
The most basic structure of all possible Web documents is
<HTML>
……………
…………..
…………..
</HTML>
Answer:

Question 2. Explain the tag < HEAD >         CBSE 2006
Answer: <HEAD> Tag
This element is a container for all the header elements. The <HEAD> tag must include a title for the document that can include scripts, styles, meta information and many more. The second line of your HTML document should be <HEAD>.

The content contained in the head section of your document provides information to the browsers and search engines but, it is not displayed directly on the Web page. The end of the head tag is indicated by </HEAD>.

e.g.
<HTML>
<HEAD>
Header information comes here
</HEAD>
</HTML>

Question 3. Distinguish between <BASEFONT> tag and <FONT> tag with the help of an example of each. CBSE 2009, 08
Answer:

<BASEFONT> tag is used to specify the default setting of the text. It takes the same attributes as <FONT> tag. The only difference is that the <BASEFONT> tag affects all the text that follows until a new tag affect that is encountered. <FONT> tag affects the text that comes upto its closing </FONT> tag.

e.g.
<HTML>
<BODY>
<BASEFONT size=“2” color=“Red">
Hi Everyone
<FONT size=“4”>
HTML is a Web language </FONT>
It is used for creating Web pages.
</BODY>
</HTML>

Here, in the above example only the text enclosed in <FONT> </FONT> is affected by font setting, rest of the text gets affected by basefont setting.

Question 4. What is a <BASEFONT> tag? Name any two attributes used with this tag. CBSE 2009
Answer: <BASEFONT> tag specifies a default font size, color and face for the font, the browser will use to render normal document text, i.e. the text, for which no other font setting has been provided. It occurs only for one time in the document. The attributes of this tag are size and face.

Question 5. Where can a comment be placed in an HTML document? How is it useful? CBSE 2008
or
How do you give a comment in HTML?
or
Why are comment included in HTML document? With the help of an example, explain how they are included in HTML code?
or
How are comments inserted in HTML code? Explain with an example. CBSE 2007, 06, 05
Answer: Comments are inserted in HTML code with the help of <!—….—> tag. To insert the text as comment, type the text between <!– and —> tag, then that text will be ignored by the browser and invisible for the user.

e.g.
<HTML><BODY>
<!--This is a comment.-->
This is a book
</BODY><HTML>

Question 6. Identify which one is an attribute or a tag?

1. Body
2. Type
3. Br
4. Link
5. Face

Answer:

1. Body – Tag
2. Type – Attribute
3. Br – Tag
4. Link – Attribute
5. Face – Attribute

Question 7. Carefully study the Web page given here. Identify 10 tags (Structural as well as formatting tags) that have been utilised in creating this Web page and write usage of each of them. CBSE 2013

Answer:

1. <HTML>……….</HTML> It encloses the entire HTML document and tells the browser that it is reading an HTML document and to display as such.
2. <HEAD>………</HEAD> It encloses the head of the HTML document and it is used to contain face information about the document.
3. <TITLE>…..</TITLE> It indicates the title of the document and appears in a browser’s bookmark file.
4. <BODY>……</BODY> It is used to enclose the body (text, images, tags, links) of the HTML document.
5. <H1>………</H1> It is used to define the heading level 1.
6. <UL>…….</UL> It is used to create an unordered list.
7. <LI>…..</LI> It is used to define each list item in the list.
8. <U>…..</U> It is used to underline the text.
9. <HR> It is used to insert a horizontal line.
10. <CENTER>….. </CENTER> This tag is used to align the text centrally.

Question 8. Explain the topmargin and leftmargin attributes of <BODY> tag. CBSE 2006
Answer:

topmargin
Sets a topmargin (distance between the top of the document and the top of the browser window) of your body element.
Syntax
<B0DY topmargin=“value”>

e.g.
<HTML>
<HEAD>
<TITLE> Topmargin </TITLE>
</HEAD>
<BODY topmargin=“65”>
LearCBSE is the best website for CBSE students.
</BODY>
</HTML>

Output

leftmargin
Sets a left hand margin (distance between the left side of the document and the left edge of the browser window) of your body element.
Syntax
<BODY 1eftmargin=“value”>

e.g. 
<HTML>
<HEAD>
<TITLE> Leftmargin </TITLE>
</HEAD>
<BODY 1eftmargin=“65”>
LearCBSE is the best website for CBSE students.
</BODY>
</HTML>

Question 9. Write HTML code to display various bullet types.
Answer:

<LI>Lotus</LI>
<LI>Rose</LI>
</UL>
<UL type = “square”>
<LI>Sun</LI>
<LI>Hoon</LI>
</UL>
</BODY>
</HTML>

Output

Question 10. Distinguish between <P> tag and <BR> tag with the help of an example. CBSE 2005
Answer: Distinguishing between <P> tag and <BR> tag are as follows:

Question 11. Give HTML code for the following output

Answer:

<HTML>
<BODY>
<UL type="disc”><B>Mazedar Restaurant
</B><LI><B>Appetizers</B>
<OL type =“i”>
<LI> Veg spring rol1s
<LI> Honey chilly
</OL>
<LI><B>Soups</B>
<UL type = “square”>
<LI> Veg hot and Sour soup </UL> <OL type = “a”>
<LI> North India <LI> South India <OL type = “1”>
< LI > I d 1 i e s <LI> Dosa
</OL> 
</OL>
</UL></BODY>
</HTHL>

Question 12. Write HTML code to display ordered lists.
Answer:

<HTML>
<HEAD>
<TITLE>Many Ordered List</TITLE>
</HEAD>
<BODY>
<I>Numbered list</I>
<OL>
<LI>Sun</LI>
<LI>Moon</LI>
</OL>
<I>Letters 1is t </1 >
<OL type = “A”>
<LI>Sun</LI>
<LI>Moon</LI>
</OL>
<I>Lowercase letters starting from 3rd 1etter</I>
<OL type = “1” start = "1”>
<LI>Sun</LI>
<LI>Moon</LI>
</OL>
<I>Roman numbers</I>
<01 type=“l”>
<LI>Sun</LI>
<LI>Moon</LI>
</OL>
<I>Lowercase roman number list starting from 5th number</I>
<OL type = “1”>
<LI>Sun</LI>
<LI>Moon</LI>
</OL>
</BODY>
</HTML>

Output

Multiple Choice Questions [1 Mark each]

Q1. HTML is a CBSE2011
(a) package
(b) software
(c) markup language
(d) None of these
Answer: (c) HTML is a markup language which is used to define the layout and attributes of WWW document.

Q2. HTML tags are enclosed in
(a) curly brackets
(b) square brackets
(c) double quotes
(d) angular brackets
Answer: (d) HTML tags are enclosed within angular brackets (< and >).

Q3. Which of the following tag identifies the document as an HTML document?
(a) <HTML>
(b) <HEAD>
(c) <BODY>
(d) <P>
Answer: (a) tag identifies the document as an HTML document.

Q4. Container elements in HTML require     CBSE 2015
(a) starting tag
(b) ending tag
(c) starting and ending tags
(d) None of the above
Answer: (c) In HTML, container elements are required as both starting and ending tags.

Q5. HTML tags are
(a) in uppercase
(b) case sensitive
(c) in lowercase
(d) not case sensitive
Answer: (d) HTML tags are not case sensitive means we can write tags either in uppercase or lowercase.

Q6. Which type of tags used by HTML?
(a) tags only for image
(b) user defined tags
(c) tags only for linking
(d) fixed tags defined by the language
Answer: (d) HTML provides predefined and fixed tags.

Q7. Which program do you need to write HTML code?
(a) Spreadsheet
(b) Access
(c) Notepad
(d) None of these
Answer: (c) From the given options, Notepad is useful program to write HTML code.

Q8. An example of HTML editor is
(a) Notepad
(b) Dreamweaver
(c) Microsoft Frontpage
(d) All of these
Answer: (d) HTML provides various text editors like Notepad, Dreamweaver etc.

Q9. To create an HTML page, you need
(a) text editor
(b) Web browser
(c) Both (a) and (b)
(d) None of these
Answer: (c) Because text editor is required to write HTML code and Web browser is needed to display the page.

Q10. Which of the following is the correct code of HTML page?

(a) <HTML>
<TITLE> Hello
</TITLE>
</HTML>

(b) <HTML>
<HEAD>
<TITLE> Hello
</TITLE>
</HEAD>
</HTML>

(c) <HTML>
<BODY> Hello
</HTML>

(d) <HTML><HEAD> Hello
<BODY>
</HTML>

Answer: (b) Because <TITLE> tag must close inside the <HEAD> tag.

Q11. Tags and text that do not display directly on the page afe placed in
(a) body
(b) table
(c) head
(d) title
Answer: (c) Information in <HEAD> tag is not displayed directly in Web page. It is used to identify the matter (tags) used in a Web page.

Q12. A Web page normally consists of
(a) head and body
(b) top and bottom
(c) body and font
(d) body and title
Answer: (a) From the given options, a Web page normally consists of head and body.

Q13. Which section is used for text and tags that are shown directly on your Web pages?
(a) Meta
(b) Head
(c) Body
(d) Table
Answer: (c) Information in <BODY> tag is directly displayed on Web pages.

Q14. Where do you place the <TITLE> tag in a HTML?
(a) BODY
(b) HEAD
(c) TITLE
(d) FONT

Answer: (b) <TITLE> tag is placed in the <HEAD> tag.

Q15. Which attribute is not supported by a <BODY> tag? CBSE 2013
(a) bgcolor
(b) size
(c) text
(d) link
Answer: (b) size is not an attribute of <BODY> tag.

Q16. What will happen if the background image is smaller than the browser’s window?
(a) It will leave a blank space at the bottom of your page
(b) It will be repeated
(c) It will be stretched
(d) It will not be displayed
Answer: (b) When the background image is smaller than the browser’s window then it will be shown in boxes in repeated pattern.

Q17. Why should you specify a background color, if you are using an image for the actual background of your page?
(a) So the text shows up better
(b) The background color will be shown until the image loads
(c) In case the image does not fit right
(d) None of the above
Answer: (b) We have to use background color because if in any case image is not displayed then atleast background color will be shown on that place.

Q18. Which attribute of <BODY> tag specifies the color of visited links in a document?
(a) vlink
(b) alink
(c) link
(d) None of these
Answer: (a) vlink attribute specifies the color of visited links in a HTML document.

Q19. Choose the correct HTML tag for the largest heading.
(a) <H2>
(b) <H4>
(c) <H6>
(d) <H1>
Answer:(d) <H1> tag provides the largest heading in HTML.

Q20. Which of the following will give smallest size of the text? CBSE 2014
(a) <H3>
(b) <H6>
(c) <H2>
(d) <H4>
Answer: (b) From the given options, <H6> tag displays the smallest size of heading text.

Q21. In a Web page, you can place
(a) 2 levels of headings
(b) 6 levels of headings
(c) 4 levels of headings
(d) 7 levels of headings
Answer: (b) Web page provides six levels of headings.

Q22. The default alignment for paragraph is
(a) left
(b) right
(c) center
(d) justified
Answer: (a) The align attribute of <P> tag provides various alignments like left, right, center and justify. But by default, its alignment is left.

Q23. Which of the following HTML container tags do you apply to text for formatting the text as a paragraph?
(a) <PARAGRAPH> ……. c/PARAGRAPH>
(b) <PARA> ………. </PARA>
(c) <P> ……… </P>
(d) None of the above
Answer: (c) <P>…….</P> is a container tag, which is used for formatting text.

Q24. Which of the following is not a container element? CBSE 2013
(a) P
(b) B
(c) OL
(d) HR
Answer: (d) HR is an empty tag because it has no closing tag.

Q25. The style element holds the document for setting
(a) font, color and alignment
(b) font, color, alignment and border
(c) color, alignment and border
(d) None of the above
Answer: (b) Because they are used to give a better look and feel to the Web documents.

Q26. The tags used for specifying the style in HTML are
(i) <B> (ii) <I> (iii) <M> (iv) <L>
Choose the correct one
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iv)
(d) (i), (ii) and (iii)
Answer: (a) Because these two tags are text formatting/styling tags.

Q27. Which of the following tag is used to make a list that lists the items with numbers?
(a) <DL>
(b) <UL>
(c) <OL>
(d) None of these
Answer: (c) <OL> is the ordered list that starts with a number like 1, A, a, i and I etc.

Q28. Which of the following is not HTML list? CBSE 2013
(a) Ordered
(b) Unordered
(c) Definition
(d) Detailed
Answer: (d) Detailed list is not a type of HTML list.

Q29. In an unordered list, it is necessary to enclose each item in CBSE 2013
(a) <LI> tag
(b) <UL> tag
(c) <I> tag
(d) <OL> tag
Answer: (a) Each item must be enclosed in <LI> tag either in ordered list or unordered list.

Q30. Which option do you have while making bulleted lists?
(a) Disc, circle, square
(b) Square, polygon
(c) Disc, circle, rectangle
(d) Disc, oval, polygon
Answer: (a) Bulleted list provides various values like disc, circle and square.

Q31. Which one of the following list type that will create a bulleted list? CBSE 2014
(a) Unordered
(b) Ordered
(c) Definition
(d) All of these
Answer: (a) Unordered list provides various types of bullets like square, disc and circle.

Q32. Which of the following will produce a solid circle bullet when given as value of type with <UL>?
(a) Circle
(b) Disc
(c) Square
(d) Rectangle
Answer: (b) A solid circle bullet use the type disc.

Q33. To create a square bulleted list, use
(a) <UL type=”circle”>
(b) <OL type= “square”>
(c) <ULtype=”square”>
(d) <UL start= “square”>
Answer: (c) Square bulleted list is the part of unordered list.

Q34. In an ordered list, each item cannot be preceded with CBSE 2013
(a) Counting numbers
(b) Arabic numbers
(c) Roman numerals
(d) Bullets
Answer: (d) In unordered list, bullets are used while counting numbers, arabic numbers and roman numbers are used in an ordered list.

Q35. To create a numbered list with A, B, … use
(a) <OL type=”A”>
(b) <OL start=”A”>
(c) <OL begin=”A”>
(d) <OL starts=“a”>
Answer: (a) The given list uses the uppercase letter for each item so, the correct syntax is <OL type=“A”>

Q36. To start a list with number 3, we should write CBSE 2015
(a) <OL start=”3″>
(b) <OLtype=”3″>
(c) <OL value=”3″>
(d) All of these
Answer: (a) The correct syntax for start a list with number 3 is <OL start = “3”>.

Q37. To start a list using circles, use
(a) <UL type=”round”>
(b) <OL start=”l”>
(c) <UL =”circle”>
(d) <UL type =”circle”>
Answer: (d) Because circular list starts with unordered list type circle.

Q38. To start a numbered list with regular numerals, use
(a) <OL type=”A”>
(b) <OL type=”r”>
(c) <OL type=”r”>
(d) <OL type=”u”>
Answer: (b) Because regular numbering is the natural numbers starting from 1, 2, 3, … etc.

Q39. If you want to make a list of items in the form of terms and their descriptions, then you can create a …………. list.
(a) ordered
(b) unordered
(c) definition
(d) nested
Answer: (c) A definition list is a list of items, with a description of each item.

The post NCERT Solutions for Class 10 Foundation of Information Technology – HTML appeared first on Learn CBSE.

NCERT Solutions for Class 10 Foundation of Information Technology – Inserting Images and Links in HTML

Very Short Answer Type Questions [1 Mark each]

Question 1. How can text be displayed in place of image for users whose browser do not support images? CBSE 2007
Answer: The alt attribute of <img> tag is used to display the text in place of image for the users whose browser do not support images.

Question 2. Write a statement in HTML that inserts an image named ‘school.jpg’ found in the ‘images’ folder of the current folder. In case the image cannot be found, it should display ‘Schools in India’.
Answer: <img src =”images\school.jpg” alt=”Schools in India”>

Question 3.  The following code is written to align the image in center in the browser’s window.
However, the>desired result is not achieved. Mention the reason.
<img src = “image.jpg” align = “center”>
Answer: The reason for not getting the desired result is that center is not a value of align attribute in <img> tag.

Question 4. Why width and height attributes are used?
Answer: The width and height attributes are used, such that downloading of an image will be faster after knowing the dimensions of the images in the browser.

Question 5. What do you mean by hypertext?
Answer: Hypertext acts as a link on which you click to navigate to the desired content.

Question 6. In HTML, how linking can be done?
Answer: In HTML, linking can be done by using anchor <a> tag followed by href attribute.

Question 7. Explain linking.
Answer: When one Web page or a text fragment is connected to another Web page, then it is called linking. It is of two types— internal linking and external linking.

Question 8. What happens when we click on a hyperlink in a Web page? CBSE 2008
Answer: When we click on a hyperlink in a Web page, it provides a link that leads from one document to another.

Question 9. Give the expansion of the following

1. alt
2. <a>

Answer:

1. alt is used for alternate text attribute.
2. <a> is used for anchor tag.

Question 10. Write the HTML command to display the following in your Web page. A² + B² CBSE 2006
Answer: The HTML command is – A² + B²

Question 11. Write the output on the Web page for the following HTML command.
<u>Atomic weight of </u>O₂
Answer: The output on the Web page will be Atomic weight of O₂

Short Answer Type Questions [2 & 3 Marks each]

Question 1. Describe the use of alt attribute with <img> tag.
Answer: The alt attribute is used to define ‘alternate text’ for an image. It tells the Website visitor, what he/she is missing on the page if the browser cannot load images. The browser will then display the altertnate text instead of the image. It is good to include alt attribute for each image on a page to improve the appearance and usefulness of the document.

Question 2. Write the HTML code to display an image on the right side of the page. CBSE 2016
Answer:

<html>
<body>
<img src="image.jpg" align="right">
</body>
</html>

Question 3. Name the values that can be assigned to align attribute of <img> tag.
Answer: The values that can be assigned to align attribute of <img> tag are as follows:

1. top
2. bottom
3. left
4. right
5. middle

Question 4. Write the HTML code to display an inline image named pencil.jpg located at C:\ in the center of your Web page. CBSE 2013
Answer:

<html>
<body>
<center>
<img src="C:\pencil.jpg">
</center>
</body>
</html>

Question 5. Define height and width attributes of <img> tag.
Answer: The width and height attributes tell the dimension of an image to the browser. Both (height and width) attributes require integer values (dimension of image in terms of either pixels or percentage of its actual size).
<img src=”picture.jpg” height = “50” width = “50”>

Question 6. Identify the errors in the following HTML code and write the correct code with each correction underlined. CBSE 2011

<html>
<title>IMAGES</head>
<body bgcolor="PICI.JPG">
<img href="ABC.JPG">
HERE IS MY IMAGE FILE
</bgcolor>
</html>

Answer:

Error 1 The <title> tag must be within <head> element.
Error 2 bgcolor attribute of body element supports a color like red, green or its color value.
Error 3 <img> tag needs a source attribute src to place an image.
Error 4 body element must be closed not bgcolor attribute.

The correct code is as follows:
<html>
<head>
<title>IMAGES</title>
</head>
<body bocolor = "yellow">
<imq src= "ABC.JPG">
HERE IS MY IMAGE FILE </body>
</html>

Question 7. Explain the need of linking between Web pages.
Answer: Linking between different Web pages is required, as when we create Websites, different html files (Web pages) are created. These files contain different modules and cannot be open individually. If we link between them, the Website becomes more productive and informative.

Question 8. How is external linking different from internal linking? CBSE 2004, 05
Answer: External link is a type of linking that goes to another Website. It is a linking of two different documents. While, internal linking is a type of linking that links pages within a single Website, various sections of same document or different document.

Question 9. Explain the given command
<a href =”wild.html”>Click Here for wild animals</a> CBSE 2006
Answer: In this command, anchor <a> tag and its href attribute is included. The text (Click Here for wild animals) will appear underlined and indicates that clicking the text activates the hypertext link. The address of the referenced document can be specified by an absolute or relative URL.
Thus, “wild.html” is an URL or Web page address and Click Here for wild animals is the hyperlinked text.

Question 10. Name the attributes of <a> tag which are used for internal linking in a Web page. CBSE 2014, 13
Answer:The attributes of <a> tag which are used for internal linking in a Web page as follows:

1. href used to specify the URL of the segment the link goes to.
2. name gives the name to the segment.

Question 11. What is the purpose of using the attribute href in <a> tag?
Answer: The href stands for Hypertext Reference. The href attribute is used with <a> tag to specify link to some other HTML page or Website.
e.g. <a href “”http://www.learncbse.in”>
click here </a> to go to learncbse.
It will display like:
click here to go to learncbse.

Question 12. Write the HTML code to create a link for school .jpg located at C:\. CBSE 2014
Answer:

<html>
<body>
<a href = "C:\school. jpg">Image</a>
</body>
</html>

Question 13. Write an simple HTML code to show an example of internal linking.
Answer:

<html>
<head><title>Internal Linking</title>
</head>
<body>
<h1>It is <a name ="top">top</a> of the page </h1>
<br><br><br><br><br><br><br><br><br><br>
<br><br><br><br><br><br><br><br><br><br>
<br><br><br><br>
<h1><a href ="#top">Top</a></h1>
</body>
</html>

Question 14. What is the purpose of mailto function?
Answer: The mailto function is used to send E-mail messages to multiple recipients. For this, we only need to type the E-mail address of the recipients in the same link separated by commas.

Question 15. Write an HTML code to show the use of mailto function.
Answer:

<html>
<head>
<title> Use of mailto </title>
</head>
<body>Send your views to
<a href= "mailto:aaa_rr@gmail.com"> aaa_rr@gmail.com< / a >
</body>
</html>

Question 16. Write the HTML code to send an E-mail to abc@xyz.com from your Web page. CBSE 2013
Answer:

<html>
<body>
<a href="mailto:abc@xyz.com">abc@xyz.oom</a>
</body>
</html>

Question 17. Distinguish between <sup> and <sub> tags with example.
Answer: Distinguishes between <sup> and <sub> tags are as follows:

Question 18. Write the full forms of: CBSE 2013

1. <sup>
2. <a>
3. <img>
4. <sub>

Answer:

1. <sup>Superscript
2. <a> Anchor
3. <img> Image
4. <sub> Subscript

Long Answer Type Questions  [5 Marks each]

Question 1. Explain various attributes of <img> tag.
Answer: 

Attributes of <img> Tag
An attribute is an extra piece of information associated with a tag that provides further details about the tag.
Following are the various attributes of <img> tag:

The src Attribute: The src (source) attribute takes URL (Universal Resource Locator) of an image file as value, which points to the direct location of an image to be displayed.
The image that you specify in your <img> tag should be in your computer otherwise the image will not be displayed and in place of image a cross mark in a box 0 will appear.

The alt Attribute: This attribute of <img> tag is used to provide alternate text when an image on a Web page cannot be displayed.
The alternative text is the text associated with an image that serves the same purpose and conveys the same essential message. As per HTML standard, alt attribute is optional but is highly recommended.

The align Attribute: This attribute is used to set the position of an image in a Web page according to the user’s requirements. In HTML, images appear inline with a single line of the text. But, HTML standard does not define a default alignment for the images with respect to other text and images in the same line.
There are some values of image alignment attribute as follows:

1. Top Alignment
2. Middle Alignment
3. Bottom Alignment
4. Left Alignment
5. Right Alignment

The width and height Attributes: When an image is added to a Web page, it is not mandatory to specify width and height of the image. At the time of loading an image, a box will appear on the place where the image will be loaded.

The border Attribute: You can set the border of an image that you want to use in your Web page. The border attribute of the <img> tag specifies the width of the border around an image. By default, an image has no border in HTML.

Question 2. Which attribute is used to specify the location of an image file in <img> tag? Explain.
Answer: The attribute you need to get an image to display on a Web page is the src attribute.
In the src attribute of the <img> tag, you can specify the path of the image that you want to add to the Web page. This may be an image in the same directory, an image somewhere else on the same server, or an image stored on another server.
The syntax for src attribute is <img src =”imagel. jpg”>

Question 3. Define various alignments of align attribute with example.
Answer: There are some values of image alignment attribute as follows:

Middle Alignment
This alignment is different in both Internet Explorer and Mozilla Firefox. In Internet Explorer, this alignment aligns the image to the middle of the tallest item in the current line. While in Mozilla Firefox, this alignment aligns the image to the baseline of the current line in which it is placed.

Example: To show middle alignment of an image.
<html>
<head>
<title> Alignment </title>
</head>
<body>
<h1> Middle Alignment </ h1>
<img src="flower2.jpg" align="middle">
A flower, sometimes known as a b'oom or blossom, is the reproductive structure found in flowering plants. The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs.
</body>
</html>

Bottom Alignment
This alignment aligns the bottom edge of the image, to the same horizontal plane as the baseline of the text. Both Internet Explorer and Mozilla Firefox treat this alignment in the same manner.

Example: To show bottom alignment of an image.
<html>
<head> <title> Alignment </title> </head>
<body>
<h1> Bottom Alignment </h1>
<img src="flower2.jpg" alt="flower" align="bottom">
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants. The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs.
</body>
</html>

Left Alignment
This alignment aligns the image to the left on the Web page respectively of the browser window.

Example: To show left alignment of an image.
<html>
<head> <title> Alignment </title> </head>
 <body>
<h1> Left Alignment </h1>
<img src="flower2.jpg" align="left">
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants. The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs.
</body>
</html>

Right Alignment
This alignment aligns the image to the right on the Web page respectively of the browser window.

Example: To show right alignment of an image.
<html>
<head> <title> Right Alignment </title> </head>
<body>
<h1> Right Alignment </h1>
Cimg src="flower2.jpg" align="right">
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants. The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs.
</body> 
</html>

Question 4. Write HTML code to illustrate

1. listed hyperlinks
2. image hyperlinks

Answer:

Listed Hyperlinks: It is noticeable that <a> tag can also be used for more complex task (as with images or with lists etc.)

Example: To show listed hyperlinks.
<html>
<head> <title> List </title> </head>
<body> <h1>List </h1>
<ul>
<li> <a href="linkl.html"><img src ="F:Fruits-wallpaper-91.jpg" align="middle" height="75" width="75">
Fruit Chart </a></li><br><br>
<li> <a href= "link2.html">
<img src="F:\vegetable.jpg" align="middle" width="75" height="75">
Vegetable Chart </a> </li > </ul>
</body>
</html>

Output:

Image Hyperlinks: Images can also be used as hyperlinks. To create image as a link, following syntax is used:
<a href = “URL”> <img src=”image1.jpg”> </a>

Example: To show image as link.
 <html>
 <head>
 < title>Image as Link</title)
 </head>
 <body>
 <a href "http://en.wikipedia.org/wiki/Tweety")
 <img src="D:\Class10\computer\tweetyl.jpg"></a>
 </body>
 </html>

Output:

Question 5. Explain the following (with example):

1. linking on same Web page.
2. linking on different Web page.

Answer:

Linking on the Same Web Page

To create an internal link, you need to use a pair of <a> tags. The first <a> tag is used to specify the name of the target location for identification purpose. It is known as target fragment. You can use the <a> tag with its name or id attribute to identify a fragment. This type of anchor is commonly called as named anchor.
The first step is to make the target fragment. The simple syntax to do so is written below:
<a name =”aa”> Part A </a>
Where, “aa” is the name of fragment/segment you want to refer (like top, bottom etc.). The second <a> tag is used to create a link to the target fragment. The simple syntax to link to the target segment is written below:
<a href = “#aa”> ClickHere </a>
In the second <a> tag, the value of href attribute with # symbol is to be specified.

Example: To show the internal linking in an HTML document.
<html>
<head><title>Internal Linking<title></head>
<body>
<h1>Linking in a page </h1>
<h3>Click here to go to the
<a href="#bottom">bottom</a> of the page.</h3>
<br>><br><br><br><br><br><br><br><br> 
<br>><br><br><br><br><br><br><br><br>
<br>><br><br><br><br><br><br><br><br>
<a name="bottom"><h3> You are at the bottom of the page.</h3></a>
</body>
</html>

Output:

Linking Sections of Different Web Pages

Internal linking enables us to link sections of different Web pages also. It can be done by specifying the name of the Web page and the section which is to be linked. To link two Web pages, you first need name to the section by using name attribute of <a> tag that you want to link. Suppose, we need to link a section of HTML1.html to HTML2.html. Create a named anchor in HTML1.html.
The syntax is given below:
<a name =”link”> Different Page </a>
After this, you have to write the code to refer to it, from Web page HTML2.html. Following is the code to do so:
<a href =”HTML1.html#link”>
Here, HTMLl.html is the name of html file to the section of which you want to link and # link is the segment name you want to link in that html file.

Multiple Choice Questions [1 Mark each]

Q1. Web browsers display images in the following format
(a) XBM
(b) JPEG
(c) GIF
(d) All of these
Answer: (d) All of these

Q2. Which tag is used to insert an image in Web page?
(a) <a>
(b) <table>
(c) <img>
(d) <p>
Answer: (c) <img> tag is used to insert inline image in a Web page.

Q3. The correct HTML code for inserting an image is CBSE 2012
(a) <img href=”image.gif”>
(b) <img> image.gif</gif>
(c) <img src = “image.gif”>
(d) <image src = “image.gif” >
Answer: (c) <img src=”image.gif “>

Q4. src attribute used with <img> tag stands for CBSE 2013
(a) screen (b) screen resolution count
(c) source (d) structure
Answer: (c) source

Q5. …………. attribute is used to specify the location of an image file.
(a) alt
(b) src
(c) align
(d) name
Answer: (b) src attribute is used to specify the location of an image file.

Q6. The text specified in the alt attribute is displayed as tooltip in
(a) Internet Explorer
(b) Google Chrome
(c) Both (a) and (b)
(d) None of these
Answer: (a) The text specified in alt attribute is displayed as tooltip in Internet Explorer only.

Q7. The alternate text of an image can be displayed by using attribute of the <img> tag.
(a) src (b) alt
(c) align (d) None of these
Answer: (b) alt attribute of the <img> tag is used to display the alternate text of an image.

Q8. alt attribute allows CBSE 2016
(a) addition of an alternate hyperlink
(b) addition of a border to image
(c) use of an alternative image in place of the specified image
(d) addition of alternative text about an image
Answer: (d) alt attribute allows addition of alternative text about an image.

Q9. The default alignment of images, that are inserted in Web page, is
(a) left
(b) right
(c) inline with text
(d) middle
Answer: (c) An image which is inserted in Web page by default placed inline with text.

Q10. Which is not a valid value in the align attribute of <img> tag? CBSE 2014,2013
(a) top
(b) center
(c) bottom
(d) right
Answer: (b) center is not a valid value in the align attribute of <img> tag. To align in center, <center> tag can be used.

Q11. Why is it important to specify width and height attribute in <img> tag? CBSE 2013
(a) To ensure that image is not copied
(b) The image will not render without these
(c) To stop the image from loading
(d) Helps the browser to load the Web page faster
Answer: (d) Helps the browser to load the Web page faster.

Q12. When creating a Web document, which unit is used to express an image’s height and width? CBSE 2013
(a) Centimetres
(b) Pixels
(c) Dots per inch
(d) Inches
Answer: (b) Image’s height and width unit are expressed in pixels or in per cent form.

Q13. The <a> tag is
(a) a container tag
(b) an empty tag
(c) a closing tag
(d) None of these
Answer: (a) <a> is a container tag, which requires starting as well as matching ending tag.

Q14. ………… is the default color of a hyperlink.
(a) Red
(b) Blue
(c) Green
(d) Black
Answer: (b) Blue

Q15. The tag used in HTML to link a Web page with other Web page is CBSE 2013
(a) <a> (b) <h> (c) <u> (d) <l>
Answer: (a) <a> anchor tag is used to create links.

Q16. Which tag tells, where a link starts? CBSE 2014
(a) <1> (b) <start>
(c) <a> (d) None of these
Answer: (c) <a> tag specify that a link starts, in which, href create a hyperlink.

Q17. Which command should be use to link a page with HTML page? CBSE 2013
(a) <a link = “page.htm” > </a>
(b) <a href = “page.htm”>page</a>
(c) <a connect = “page.htm”></a>
(d) <a attach = “page.htm”></a>
Answer: (b) <a href=”page.htm”>page</a>

Q18. With which code you .can make an image works as link? CBSE 2016
(a) <a href = “URL”>Text</a>
(b) “<a href=”ABC.html”><img src =”graphic.gif”>Click Here</a>
(c) <a ref=mailto:<img src = graphic.gif>Click Here</a>
(d) None of the above
Answer: (b) With <a href=”ABC.html”><img src= “graphic.gif >Click Here</a> image works as link.

Q19. To create a hyperlinked image
(a) the image tag should be within anchor tag
(b) the anchor tag should be within image tag
(c) the image tag should be before the anchor tag
(d) the image tag should be after the anchor tag
Answer: (a) The image tag should be within anchor tag to create hyperlinked image.

Q20. For internal linking, the section names are provided by attribute of <a> tag.
(a) title
(b) href
(c) name
(d) None of these
Answer: (c) For internal linking, section names are provided by name attribute.

Q21. Is it possible to link within the current page?
(a) No
(b) Only in framesets
(c) Yes
(d) None of these
Answer: (c) Yes, it is possible to link within the current page, which is called internal linking.

Q22. ………. attribute of the <a> tag is used to name a section in a Web page to create an internal link.
(a) href
(b) name
(c) align
(d) link
Answer: (b) name attribute is used to create an internal link.

Q23. …………….. attribute is used to set the color of a link while it is active.
(a) vlink
(b) alink
(c) Both
(a) and (b)
(d) None of these
Answer: (b) alink attribute is used to set the color of link while it is active.

Q24. The attribute which is used to send E-mails through a Website.
(a) tomail
(b) mailto
(c) Both
(a) and (b)
(d) None of these
Answer: (b) mailto attribute is used to send E-mails through a Website.

Q25. Choose the correct syntax to create an E-mail link. CBSE 2014
(a) <a href = “abc@xyz.com”>
(b) <a href = “mailto:abc@xyz.com”>
(c) email = “abc@xyz.com”>
(d) <amail = “abc@xyz.com”>
Answer: (b) <a href = “mailto:abc@xyz.com”>

Q26. To display (X+Y)², correct HTML code is         CBSE 2013
(a) _(X+Y)2
(b) X+Y< sup > 2 </sup >
(c) (X+Y)²
(d) ^{(X +Y)2}
Answer: (c) (X+Y) ² code is correct because superscript have to be placed in between ^and tags.

Fill in the Blanks [1 Mark each]

Q1. The <img> tag is an ………… tag, that means it has no closing tag.
Answer: empty

Q2. <img> tag is used for …………. images. CBSE 2014
Answer: displaying

Q3. …………… tag is used to create inline images. CBSE 2013, 2012
Answer: <img>

Q4. ……………. is an attribute of the <img> tag which specifies the location or URL of the image to be displayed.
Answer: src

Q5. An attribute is an extra piece of information associated with a …………….
Answer: tag

Q6. The ait attribute provides …………… for an image.
Answer: alternative information

Q7. The value for alt attribute is a text string of upto ………….. characters.
Answer: 1024

Q8. An image to be displayed in a Web page has to cover 25% of the browser window horizontally and 50% vertically. The attributes ………… and ………….of the <img> tag would be used for achieving this.
Answer: height, width

Q9. attribute is used to give border to an image. CBSE 2016
Answer: border

Q10. ………… is a word or image that when clicked take us to another Web page. CBSE 2013
Answer: Hyperlink

Q11. ………… tag is used to connect Web pages. CBSE 2014
Answer: <a>

Q12. ……. are used to connect Web pages. They are created with <a> tag. CBSE 2016
Answer: Hyperlinks

Q13. The …………. tag is considered to establish a hypertext relationship between the current document and another URL.
Answer: <a>

Q14. The ………….. attribute is used for specifying the URL of the anchor tag.
Answer: href

Q15. An ……….. link allows a link to another Web page or another Website. CBSE 2011
Answer: external

Q16. The …………….. attribute of <a> tag is used to provide information or a title for the linked document or Web page.
Answer: title

Q17. An link allows a link to another section on the same or different Web page.
Answer: internal

Q18. A visited link on a Website is generally underlined and …………… in color.
Ans. purple

Q19. The default color of alink attribute is ………… .
Answer: red

Q20. ………… is used to change the color of a visited link. CBSE 2016
Ans. vlink

Q21. Using the ………… type URL, you can create the E-mail hyperlink.
Answer: mailto

Q22. The tag ……….. is used to create superscripts and …………. tag is used to create subscripts on a Web page.
Answer: <sup>, <sub>

True or False [1 Mark each]

Q1. You can have inserted an image in your Web page which is physically present in your computer.
Answer: True With the help of <img src=”image URL”>, we can insert an image in Web page which is present in our computer.

Q2. If the image you are loading in the Web page is not available, then you want a text to appear in the image placeholder, text attribute lets you define this text.
Answer: False The alt attribute is used to define text to appear in the image placeholder, if image is not visible for any reason.

Q3. No value is specified with alt attribute of <img> tag. CBSE 2012
Answer: False alt attribute provides alternate text for an image if the image is not visible on Web page for any reason.

Q4. String as a value of alt attribute must be enclosed in quotation marks.
Answer: True alt attribute contains string which must be enclosed in quotation marks.

Q5. The general syntax for inline image is <img src = “file name” >.
Answer: True At the place of file name, path of the image is specified. If the image is in the same folder as HTML file, it is not needed to specify full path of an image.

Q6. The default alignment of image is right. CBSE 2014
Answer: False There is no default alignment of image with respect to text in HTML.

Q7. It is not important to specify an integer value as the width of the border of an image.
Answer: False Width takes an integer values that are in pixels.

Q8. The align attribute of the <img> tag is used to specify the text that is to be displayed in case the browser that does not support graphics.
Answer: False alt attribute is used to specify the text that is to be displayed in case the browser which does not support graphics.

Q9. We can put a border around an image by using width attribute. CBSE 2013
Answer: False We can put a border around an image by using border attribute.

Q10. border is an attribute of <a> tag. CBSE 2012
Answer: False border is an attribute of <img> tag.

Q11. The <a> tag is called the align tag. CBSE 2011
Answer: False The <a> tag is called anchor tag.

Q12. The anchor tag <a> signals the beginning of the text.
Answer: False Anchor tag is used to create hyperlinks not text.

Q13. The color of the hyperlinks in an HTML document can be changed.
Answer: True We can change the color of hyperlinks in HTML document.

Q14. Hyperlinks can also be created for links within the same document. Linking within the same document is called external linking.
Answer: False Linking within the same document is called internal linking.

Q15. It is not possible to create link within current document. CBSE 2012
Answer: False You can link various sections of the current document together, which is called internal linking.

Q16. The name attribute of the <a> tag allows the user to create links within the same document. CBSE 2011
Answer: True Because name attribute defines a name of a section in a document.

Q17. You should include a mailto function in the body of your document to allow user to respond to your Web page.
Answer: True The mailto function is used to send E-mails from the Website.

The post NCERT Solutions for Class 10 Foundation of Information Technology – Inserting Images and Links in HTML appeared first on Learn CBSE.

NCERT Solutions for Class 10 Foundation of Information Technology – Societal Impacts of IT

Very Short Answer Type Questions [1 Mark each]

Question 1. Define virus.
Answer: A virus is a harmful program, which on entering a computer, starts creating copies of itself. It then attacks by corrupting the executable files and folders saved on the computer.

Question 2. List the different types of computer viruses.
Answer:

1. File system viruses
2. Boot sector viruses
3. Macro viruses

Question 3. Name some forms of virus attacks.
Answer: Worms, Trojan horse, Computer Virus etc.

Question 4. Give some examples of computer worms.
Answer: MS-Blaster, Mellisa worm, SQL Slammer worm are the common examples of worms.

Question 5. Explain denial of service attack.
Answer: A denial of service attack is a type of attack that consumes all the resources of a computer.

Question 6. What is used to identify, prevent and take action against malicious programs, such as viruses and worms, by deactivating or deleting them?
Answer: Antivirus is used to identify, prevent and take action against malicious programs such as viruses and worms, by deactivating or deleting them.

Question 7. Describe hacking.
Answer: Hacking is the practice of modifying the features of a system, in order to accomplish a goal outside of the creator’s original purpose.

Question 8. What is the meaning of backup? CBSE 2013
Answer: Backup is a process of making an extra copy of the data on a computer and storing it in a different location on the computer or in an external device.

Question 9. What are the types of data backup?
Answer: There are two types of data backup:

1. Full backup
2. Differential backup

Question 10. Can you backup the files while your computer is running?
Answer: Yes, we can safely backup open files and programs while they are running.

Question 11. What is encryption of data? CBSE 2014
Answer: Encryption refers to scrambling of data in some encoded format so that it may be transmitted over networks.

Question 12. A digital signature is issued by which organisation?
Answer: A digital signature is«an electronic file that is issued by a Certification Authority. (CA).

Question 13. Name two other means of online security measures.
Answer: Digital signature and Digital certificate

Question 14. Which security provision is used to ensure data integrity and authentication?
Answer: A digital signature helps the user to ensure data integrity and authentication.

Question 15. Give any two shortcomings of online purchase. CBSE 2014
Answer:

1. Cannot see the product in reality before a purchase.
2. You do not receive the product immediately, there is always some delay.

Short Answer Type Questions [2 & 3 Marks each]

Question 1. How does a virus affect your computer?
Answer: Virus is a software used to infect a computer. After virus code is written, it is buried within an essential programmed. Once the programmed is executed, the virus code is activated and attack copies itself to other programs.

Question 2. Give three guidelines to prevent the virus attack.
Answer: Three guidelines to prevent the virus attack are as follows:

1. Avoid the temptation to open unexpected E-mail attachments and downloads from unreliable sources. Resist the urge to double click everything in your mailbox. If you get an unexpected file attachment, send an enquiry E-mail to its sender. Ask him about the nature and function of the file attachment.
2. In stable reliable antivirus, scanning software and download its updates regularly.
3. Scan files downloaded from the Internet or other external sources.

Question 3. If your computer attacked by a trojan horse virus, what damage it may cause?
Answer: If your computer attacked by a trojan horse virus, it can:

1. Steal passwords
2. Copy sensitive data
3. Carry out any other harmful operations etc.

Question 4. Write minimum three ways by which a virus can spread to other systems.
Answer: Three ways by which a virus can spread to other systems are as follows:

1. When an infected file is copied through network.
2. When virus file is downloaded from Internet.
3. When infected file is copied from floppy disk, USB, DVD etc.

Question 5. Write any two tips to avoid spams. CBSE 2016
Answer: You can use the following guidelines to avoid spam, they are as follows:

1. Keep your E-mail address private.
2. Using appropriate filters to find and alter you about spam.

Question 6. What are the primary interest of online attackers in spyware?
Answer: Primary interest of online attackers in spyware is using it to steal personal information for financial crimes such as carding and identity theft or to sell that information to someone else who then executes more traditional financial crimes.

Question 7. What does an antivirus software do? CBSE 2014
or
What does an antivirus software do? Explain in brief with any two points. CBSE 2013
Answer:

1. Antivirus software is a computer program that detects, prevents and takes action to disarm or remove malicious software programs, such as viruses and worms.
2. Displays health of your computer system.

Question 8. What precaution you should take before copying file from an external storage media?
Answer: Precaution should be taken to run an antivirus program before copying any file from floppy disk, USB, DVD etc. Also, we have to run antivirus program weekly to scan all the drives in the system.

Question 9. List some commonly available antivirus programs.
Answer: Some of the commonly available antivirus programs in the market are as follows:

1. Symantec Norton antivirus
2. AVG antivirus
3. McAfee scan
4. Quick Heal

Question 10. Define information security.
Answer: Information security is all about protecting and preserving information. It’s all about protecting and preserving the confidentiality, integrity, authenticity, availability and reliability of information.

Question 11. Differentiate between full backup and differential backup.
Answer: Differences between full backup and differential backup are as follows:

Question 12. Write differences between online backup and offline backup. CBSE 2014
Answer: Differences between online backup and offline backup are as follows:

Question 13. List two advantages of online backup. CBSE 2012, 2013
Answer: Two advantages of online backup are as follows:

1. By having your data stored on a remote hard drive, you run little as there is no risk of losing your data as a result of fire, theft or any other disaster.
2. No hardware is needed to maintain or repair the backup.

Question 14. Can firewalls detect virus?
Answer: Firewalls do not screen computer viruses.
As the location of firewalls is a good place for scanning, some firewalls has plug-in virus scanning module.
And some programs scan virus at a point either before or after a firewall.

Question 15. Mention three societal impacts of IT.
Answer: The societal impacts of IT are as follows:

1. Opportunities for people with disabilities through artificial intelligence.
2. Quality of life improvements due to E-Commerce over Internet.
3. Crime fighting and other benefits.

Question 16. Why should we frequently take backup of our data?
Answer: We frequently take backup of our data because

1. The hard drive of our computer may fail.
2. The data on our computer may get corrupted for a variety of reasons.
3. Data loss due to fire, natural disasters etc.

Question 17. Differentiate between digital certificate and digital signature. CBSE 2013
Answer: Differentiate between digital certificate and digital signature are as follows:

Question 18. Name one specific software/tool for each of the following categories: CBSE 2011

1. Antivirus software
2. Data recovery tool
3. Online backup tool

Answer:

1. Antivirus software – Quick Heal
2. Data recovery tool – NTFS Reader
3. Online backup tool – Dropbox

Question 19. Give the three terms related to the following:

1. Attacks
2. Backup
3. Security software

Answer:

1. Attacks Trojan horse, Worm, Denial of Service.
2. Backup Online backup, Full backup, Differential backup.
3. Security software Digital signature, Firewall, Antivirus.

Question 20. Name four data backup devices/medium. CBSE 2016
Answer: Four storage media on which data backup may be taken are as follows:

1. DVD (Digital Versatile Disk)
2. External hard disk
3. USB flash drive
4. Memory stick

Long Answer Type Questions  [5 Marks each]

Question 1. What are the common symptoms of a virus attack?
Answer: Symptoms of Computer Viruses Attack
The list of symptoms of computer viruses attack, which indicate that your system is infected with a computer viruses are as follows:

1. Odd messages are displaying on the screen.
2. Some files are missing.
3. System runs slower.
4. PC (Personal Computer) crash or restart again and again.
5. Drives are not accessible.
6. Antivirus software will not run or installed.
7. Unexpected sound or music plays.
8. The mouse pointer changes its graphic.
9. Receive strange E-mails containing odd attachments or viruses.
10. PC starts performing functions like opening or closing windows, running programs on its own.

Question 2. What are the various measures that should be taken to prevent spyware from overtaking your system?
Answer: Preventions of Spyware
Due to the seriousness of spyware and the harm, it can affect your system and personal information, it is highly recommended you to take the given measures to prevent spyware from overtaking your system:

• Download and install anti-spyware software: Most antivirus applications are effective in identifying different types of malware, including spyware, but may not detect all spyware variants. Once you install the anti-spyware software on your computer, you must keep your anti-spyware application updated to keep up with the latest forms of spyware.
• Be cautious when Web surfing: The best defense against spyware is not to download it in the first place. Spyware is often installed on your computer when you visit an infected or malicious Website.

Therefore, you should exercise caution with links to Websites from unknown sources. In addition, you should only download programs from trustful Websites. When downloading a specific program, ensure that you are not downloading pirated software. Spyware can be distributed by exploits, that promote software piracy.

• Lookout for pop-ups: Malware can lure you into installing spyware on your computer by prompting you with a pop-up window. If you see an unwanted or random pop-up alert, do not click “Agree” or “OK” button to close the pop-up window. This will actually install the malware on your computer. Instead, press Alt + F4 or click on the red “X” on the corner on the pop-up alert to close the window.
• Keep current with operating system updates: Important system updates provide significant benefits such as improved security. Just as with any antivirus and anti-spyware software, not keeping up with operating system updates will make your PC vulnerable to the latest malware threats.
• Harden your browser settings: Updated Web browsers may help to prevent exploitation by taking several defensive steps against spyware. Most Web browsers will warn you of executable programs and will suggest a safe course of action. In addition to having an updated Web browser, ensure that you have properly configured your browser and that all of your plug-ins and add-ons are updated, including Java, Flash and Adobe products.
• Enable your firewall: Firewalls monitor the network and are capable of blocking suspicious traffic, which can prevent spyware from infecting your system.

Question 3. Differentiate between hackers and crackers.
Answer: Differences between hackers and crackers are as follows:

Question 4. Explain SET, PCI and Kerberos.
Answer:

• PCI (Peripheral Component Interconnect) is a computer bus for attaching hardware devices in a computer. These devices can take either the form of an integrated circuit fitted onto the motherboard itself, called a planer device in the PCI specification or an expansion card that fits into a slot.
• SET (Secure Electronic Transaction) protocol, which is developed by Visa and Mastercard uses encryption for privacy and digital certificates to verify the three parties -the bank, the customer and the merchant. It ensures secure transactions online.
• Kerberos is a third-party authentication that validates the clients over the network and provides secure communication or access to network resources.

Question 5. Write a short note on social networking.
Answer: It is a grouping of individuals into specific groups, like small rural communities or a neighbourhood subdivision, if you will. A social networking service is an online service, platform or site that focuses on facilitating the building of social networks or social relations among people.
e.g. people who share interests, activities, backgrounds or real life connections. When it comes to online social networking, Websites are commonly used. These Websites are known as Social Sites. The most popular social sites are currently Facebook, MySpace, Orkut etc.
These Websites provide users with simple tool to create a custom profile with text and pictures. Typical profile includes basic information about user, atleast one photo and possibly a blog or other comments published by the user. It may include videos, photos albums, online applications as in Facebook or custom layout (in MySpace). After creating a profile, user can send message to other users and leave comments directly on friends’ profiles.

Question 6. Write the benefits of ICT in education and healthcare.
Answer: Benefits of ICT
ICT has become an integral part of our daily life. And, it has benefited the common man in various ways in every field of life. Some of them are as follows:

In Education
The main purpose of the strategy for ICT implementation in education is to provide the prospects and trends of integrating ICT into the general educational activities.

Some benefits of ICT in education are as follows:

1. There is no time boundation on an individual for getting educated by a teacher. A person can attend a class anytime and anywhere.
2. Teachers can create interactive classes and make the lessons more interesting.
3. Generally, students find images and graphical representation of concepts, more interesting as compared, to the theoretical knowledge. And, using ICT, teachers can explain even the most complex concept in a very simplified manner using graphics, videos and animations.
4. An individual can learn on pace he/she is comfortable.
5. Learning resoures can be accessed remotely.

In Healthcare
Some benefits of ICT in healthcare are as follows:

1. Automated hospital information systems can help to improve quality of care.
2. Decreased costs of treatment.
3. ICT has significantly enhanced the services being provided and brought behavioural changes.
4. This technology helps doctors, hospitals, the general public and all other medical care providers.
5. Pharmaceutical industry is the industry that enjoys the biggest benefits of ICT.
6. ICT has made E-Health possible.

Question 7. “Virtual schools are better than traditional schools.” Write reasons to support this statement.
Answer: A virtual school is a learning environment offered entirely on the Internet. All student services and courses are conducted through Internet technology. The virtual school differs from the traditional school through the physical medium that links administrators, teachers and students. It refers to an institution that is not “brick and mortar” bound.

Advantages
The advantages of virtual schools are as follows:

1. Individualised instruction for all students.
2. Lessons can be taught in a way that benefits students with various learning abilities.
3. More time can be spent on lessons that are more difficult for students.
4. Flexibility for the students to learn whenever and wherever they want.
5. Students are self-directed and mature quicker as they manage their studies.
6. Students can access learning 24 hours a day and learn at their own pace.

Disadvantages
The disadvantages of virtual schools are as follows:

1. Undisciplined students will not succeed in the online environment.
2. Puts more stress on the parents to provide guidance and tutoring.
3. Parents need to monitor the student all day long as opposed to dropping the student at school where the student is monitored by teachers and staff.
4. Students are more isolated and might not developed properly socially.
5. Students would not receive personal one-on-one time with teachers.

Question 8. Give one word answer CBSE 2012

1. Another name for junk mails.
2. It is doing business online.
3. It is the crime committed using computers and Internet.
4. The programmer that breaks into secure systems with non-malicious intentions.
5. Type of malware that is installed on user’s computer and collects information about user without his consent.

Answer:

1. Spam
2. E-Business/E-Commerce
3. Cyber crime
4. Hacker
5. Spyware

The post NCERT Solutions for Class 10 Foundation of Information Technology – Societal Impacts of IT appeared first on Learn CBSE.

How do Organisms Reproduce – CBSE Notes for Class 10 Science

CBSE NotesCBSE Notes ScienceNCERT Solutions Science

1. Reproduction is the process by which a living organism is able to produce new individuals of its own kind. Unlike other life processes such as nutrition, respiration, etc., it is not essential to, maintain the life of an individual organism. But it is important for the existence and continuity of the species.

2. Reproduction involves the creation of DNA copy and additional cellular apparatus by the cell involved in the process.

3. The process of DNA copying leads to variations. This inbuilt tendency for variations during reproduction is the basis for evolution.

4. Living organisms’ reproduce mainly through :
(i) Asexual reproduction
(ii) Sexual reproduction

5. ASEXUAL REPRODUCTION
(a) Single ceiled organisms reproduce through following ways:

(ii) Budding (also by multicellular organisms)
(iii) Spore formation (also by multicellular organisms)
(b) Asexual reproduction by multicellular organisms:
(i) Fragmentation and Regeneration

6. Fission: In unicellular organisms when cell becomes fully mature, it splits into two or more parts. It is called the fission. In organisms such as Amoeba, splitting can take place in any plane. But in organisms like Leishmania, having whip like structure at one end of the cell, binary fission occurs in a definite orientation in relation to these structures.

7. Regeneration : It is the ability to give rise to new organism. When the individual is cut or broken up into many pieces. It can be seen in Hydra and Planaria and is known as regeneration.
Regeneration is carried out by specialised cells. These cells proliferate and rqgkeJarge numbers of cells. From this mass of cells, different cells undergo changes to become various cell types and tissues. These changes take place in an organised sequence referred to as ” development. However, regeneration is not the same as reproduction, since most organisms would not normally depend on being cut up to be able to reproduce.

8. Budding: Organisms such as Hydra use regenerative cells for reproduction in the process of budding. In Hydra, a bud develops as an outgrowth due to repeated cell division at one specific site. These buds develop into tiny individuals and when fully mature, detach from the parent body and become new independent individuals.

9. Spore Formation (Sporulation): Some bacteria and lower organisms make spores. During spore formation, knob like structure called sporangium develops from the fungal hypha. Sporangia contain spores that eventually develop into new individual. The spores are covered by thick walls that protect them until they come in contact with moist surface or substratum and can begin to grow.

10. Fragmentation : It can be seen in Spirogyra. During this process filament of spirogyra simply breaks up into smaller pieces upon maturation. These pieces or fragments grow into new individuals. This process occurs under favourable conditions of moisture, temperature, light and nutrient availability.

11. Vegetative propagation: It is the simplest method of reproduction in some higher plants in which new plant is produced from any vegetative part of the plant such as root, stem, leaf, etc.
Advantages of vegetative propagation : Vegetative propagation is useful for plants those have lost the capacity to produce seeds, e.g. banana, rose, jasmine. Moreover, all plants produced are genetically similar to the parent plant.
Natural Vegetative Propagation: In some plants like guava, sweet potato, dahlia, roots sprout and grow into new plants during favourable conditions. In some other,stems grow horizontally and develop root below and leaves above the ground. Many other common examples of vegetatively propagating plants are onion, banana, garlic, ginger, turmeric, bryophyllum and water hyacinth.

12. Vegetative propagation in Bryophyllum: Bryophyllum reproduces by the vegetative propagation method. During this method, buds produced in the notches along the leaf margin of bryophyllum fall on the soil and develop into new plants.

13. SEXUAL REPRODUCTION :
Sexual reproduction involves two individuals for producing a new individual. Sexual reproduction begins with fertilization, which is defined as the union of two different gametes. The motile germ-cell fptrUeh or sperm) is called the male gamete and germ-cell containing stored food (egg or ovum) is called the female gamete. The process of fusion of two gametes is called fertilization. After fertilization, a zygote is formed , which develops into a new organism.

14. Sexual reproduction in Plants : The flowering plants or angiosperms bear special reproductive parts located in the flower. Various parts of flower are; sepals, petals, stamens and carpels.
Most flowers have both male and female reproductive organs. The flower may be unisexual (papaya, watermelon) when it contains either stamen or carpel or bisexual (Hibiscus, Mustard) when it contains both stamens and carpels. It has male reproductive part cal led stamen and a female reproductive part called carpel. Carpel is made of three parts. The swollen bottom part is the ovary, middle elongated part is the style and the terminal part which may be sticky is the stigma. The ovary contains ovules and each ovule has an egg cell. Each stamen consists of stalk called filament, and a flattened fertile top called anther. The anthers produce the pollen grains. The pollen grains produce male gametes which fuse with (egg cel I) female gamete present in the ovule. This fusion of the germ-cells or fertilization gives zygote which grows into a new plant. Pollination: It is the process of transfer of pollen grains from the anther to the stigma of flower. If this transfer of pollen occurs in the same flower, it is referred to as self-pollination, whereas if the pollen is transferred from one flower to another, it is known as cross-pollination. This transfer is carried out by different agencies like wind, water, insects or animals.
Fertilization : A tube grows out of pollen grain and travels through the style to reach the female germ-cells present in ovule in the ovary. Out of two male gametes present in pollen tube one fuses with egg to form zygote. This fusion is called fertilization. After fertilization, the zygote divides several times to form an embryo within the ovule. The ovule develops a tough coat and gradually turns into a seed. The ovary grows rapidly and ripens to form a fruit. Meanwhile the petals, sepals, stamens, style and stigma may shrivel and fall off.

15. Reproduction in human beings : The reproductive organs of human beings are called gonads. These are testes in male and ovaries in female. The male gonad produces sperms and female gonad produces ova (eggs) at the age of puberty (after attainment of sexual maturity). Various changes occur in girls and boys at this age.

16. Male Reproductive System consists of the following organs:
Testes: A pair of testes are situated in scrotum that lie outside the abdominal cavity and behind the penis. Testes produce sperms and hormone, Testosterone hormone. Testosterone brings about changes in appearance of boys at the time of puberty.

VAS deferens: From each testis, a duct arises which is known as vas deferens which unites with a tube coming from urinary bladder. It brings sperms from testis.
Urethra: Vas deferens tube opens into a common tube called urethra. It runs through a muscular organ called Penis. Penis is male copulatory organ.
Accessory Glands: Glands like prostate and seminal vesicles and Cowper’s gland add their secretions which make transport of sperms easier and this fluid also provides nutrition.

17. Female Reproductive System : It consists of the following organs:

Ovaries: Paired ovaries are located in the abdominal cavity near the kidney. Ovaries produce female gamete (ovum or egg) and secrete female hormones (estrogen and progesterone). One egg is produced every month alternately by one of the ovaries.
Fallopian Tube: The egg is carried from the ovary to womb/uterus through a thin oviduct or fallopian tube.
Uterus: The two oviducts unite into an elastic bag like structure known as the uterus.
Vagina : Uterus opens into vagina. It is female copulatory organ.

18. Sexual Cycle in female: After puberty, only one egg is produced alternately from one ovary after a period of 28 days. Egg in fallopian tube encounter sperms which enter through the vaginal passage during sexual intercourse. This fertilized egg (zygote) gets implanted in the lining of uterus which later forms embryo. Embryo gets nutrition from the mother’s blood with the help of special tissue called placenta.
If the egg is not fertilized, if lives for about one day since the ovary releases one egg every month, the uterus prepares itself every month to receive the fertilized egg. Thus, its lining becomes thick and spongy. If it does not get zygote, the developed lining slowly breaks down and comes out through vagina as blood and mucus. This cycle takes place roughly every month and is known as menstruation. It usually lasts for about 2-5 days.

19. Reproductive Flealth: Reproductive organs need a lot of care and hygiene. Otherwise they are susceptible to many infections or diseases. The diseases which spread through sexual routes are known as sexually transmitted diseases e.g., bacterial infections like syphilis, gonorrhoea and viral infections such as warts and HIV- AIDS. Condom helps to prevent transmission of many of these infections to some extent.
Frequent pregnancy causes many health problems and also adds to an already exploding population. Many ways have been devised to avoid pregnancy. Contraception can be achieved by:
• Mechanical barrier method (use of condoms).
• Chemical methods (use of pills).
• Use of contraceptive devices (copper-T).
• Surgical methods (vasectomy in males and tubectomy in females)

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NCERT Solutions for Class 10 Science – Chapter 12: Electricity

Page 200

What does an electric circuit mean?
Electric circuit is a continuous and closed path made of conducting wires, through which the electric current flows. It comprises a cell, ammeter, voltmeter, plug key, etc.
Define the unit of current.
SI unit of electric current is ampere (A).
Ampere is the flow of electric charges through an area at the rate of one coulomb per second, i.e. if 1 coulomb of electric charge flows through a cross-section of wire for 1 second, then it would be equal to 1 ampere.

Page 202

Question 1:
Name a device that helps to maintain a potential difference across a conductor.
Answer:
Cell or battery eliminator.

Question 2:
What is meant by saying that the potential difference between two points is 1 V?
Answer:
As we know that V = W / q
Thus, the potential difference between two points is one volt when one joule of work is done to carry a charge of one coulomb between the two points in the electric field.

Question 3:
How much energy is given to one coulomb of charge passing through a 6 V battery?
Answer:

Page 209

Question 1:
On what factors does the resistance of a conductor depend?
Answer:
Resistance of a conductor depends upon:
(i) Resistivity of the material.
(ii) Length of the conductor.
(iii) Cross-sectional area of the conductor.

Question 2:
Will current flow more easily through a thick wire or thin wire of the same material when connected to the same source? Why?
Answer:
The current flows more easily through a thick wire than through a thin wire because the resistance of thick wire is less than that of a thin wire as R ∝ 1/A.

Question 3:
Let the resistance of an electrical component remains constant while the potential difference across the two ends of the component decreases to half of its former value. What change will occur in the current through it?
Answer:

Hence, the current through an electrical component also becomes half of its previous value.

Question 4:
Why are the coils of electric toasters and electric irons made of an alloy rather than a pure metal?
Answer:
The coils of electric toaster and electric iron are made of an alloy rather than a pure metal because of the following reasons;
(i) The resistivity of an alloy is higher than that of a pure metal.
(ii) It has high melting point and does not oxidise.

Question 5:
Use the data in Table 12.2 of NCERT book to answer the following:
(a) Which among iron and mercury is a better conductor?
(b) Which material is the best conductor? ‘
Answer:
(a) Iron because its resistivity is less than mercury.
(b) Silver is the best conductor as it has least resistivity.

Page 213

Question 1:
Draw a schematic diagram of a circuit consisting of a battery of three cells of 2 V each, a 5 Ω resistor, a 8 Ω resistor and a 12 Ω resistor and a plug key, all connected in series.
Answer:

Question 2:
Redraw the circuit of the above question, putting in an ammeter to measure the current through the resistors and a voltmeter to measure the voltage across the 12 resistor. What would be the reading in the ammeter and the voltmeter?
Answer:

Total resistance of the circuit = R
Since all the three resistors are connected in series, so, the equivalent resistance R is equal to the sum of all resistance.
R = 5 Ω + 8 Ω + 12 Ω = 25 Ω

Page 216

Question 1:
Judge the equivalent resistance when the following are connected in parallel.
(a) 1 Ω and 10⁶ Ω
(b) 1 Ω , 10³ Ω and 10⁶ Ω
Answer:
Equivalent resistance in parallel combination of resistors is always less than the least resistance of any resistor in the circuit.
Hence, in both the given cases, the equivalent resistance is less than 1 Ω.

Question 2:
An electric lamp of 100 Ω, a toaster of resistance 50 Ω and a water filter of resistance 500 Ω are connected in parallel to a 220 V source. What is the resistance of an electric iron connected to the same source that takes as much current as all three appliances and what is the current flows through it?
Answer:

Question 3:
What are the advantages of connecting electrical devices in parallel with the battery instead of connecting them in series ?
Answer:
Advantages of connecting electrical devices in parallel:
(i) When the appliances are connected in parallel with the battery, each appliance gets the same potential difference as that-of battery which is not possible in series connection.
(ii) Each appliance has different resistances and requires different currents to operate properly. This is possible only in parallel connection, as in series connection, same current flows through all devices, irrespective of their resistances.
(iii) If one appliance fails to work, other will continue to work properly.

Question 4:
How can three resistors of resistances 2 Ω, 3 Ω and 6 Ω be connected to give a total resistance of (a) 4 Ω (b) 1 Ω?
Answer:
(a) In order to get 4 Ω, resistance 2 Ω should be connected in series with the parallel combination of 3 Ω and 6 Ω.

Question 5:
What is (a) the highest (b) the lowest total resistance that can be secured by combination of four coils of resistances 4 Ω, 8 Ω, 12 Ω, 24 Ω?
Answer:
(a) The highest resistance is secured by combining all four coils of resistance in series.
R_s = 4 Ω+ 8 Ω + 12 Ω + 24 Ω = 48 Ω
(b) The lowest resistance is secured by combining all four coils of resistance in parallel.

Page 218

Question 1:
Why does the cord of an electric heater not glow while the heating element does?
Answer:
The cord of an electric heater is made up of metallic wire such as copper or aluminum which has low resistance while the heating element is made up of an alloy which has more resistance than its constituent metals. Also heat produced ‘H’ is

H = I²Rt

Thus, for the same current H oc R, so for more resistance, more heat is produced by heating element and it glows.

Question 2:
Compute the heat generated while transferring 96000 C of charge in one hour through a potential difference of 50 V.
Answer:

Question 3:
An electric iron of resistance 20 Q takes a current of 5 A. Calculate the heat developed in 30 s.
Answer:
Given R = 20 Ω, I = 5 A, t = 30 s
H = I²Rt = (5)² x 20 x 30 = 15000 J = 1.5 x 10⁴ J

Page 220

Question 1:
What determines the rate at which energy is delivered by a current?
Answer:
Electric power determines the rate at which energy is delivered by a current.

Question 2:
An electric motor takes 5 A from a 220 V line. Determine the power of the motor and the energy consumed in 2 h.
Answer:
Given I = 5 A, V = 220 V, t = 2 h Power,
p = VI = 220 x 5 = 1100 W
Energy consumed = Vlt = Pt
= 1100 x 2 = 2200 Wh

TEXTBOOK QUESTIONS

Question 1:
A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R’, then the ratio R/R’ is

Answer:

Question 2:
Which of the following terms does not represent electrical power in a circuit?
(a) I²R
(b) IR²
(c) VI
(d) V^2/R
Answer:
(b) P = V^2/R = I²R = VI Option (b) does not represent electrical power.

Question 3:
An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be
(a) 100 W
(b) 75 W
(c) 50 W
(d) 25 W
Answer:

Question 4:
Two conducting wires of same material and of equal lengths and diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be
(a) 1:2
(b) 2:1
(c) 1:4
(d) 4:1
Answer:

Question 5:
How is a voltmeter connected in the circuit to measure the potential difference between two points?
Answer:
A voltmeter is connected in parallel across any two points in a circuit to measure the potential difference between them with its +ve terminal to the point at higher potential and -ve terminal to the point at lower potential of the source.

Question 6:
A copper wire has a diameter 0.5 mm and resistivity of 1.6 X 10^-8 Ωm. What will be the length of this wire to make its resistance 10 Ω? How much does the resistance change if the diameter is doubled?
Answer:

Question 7:
The values of the current I flowing in a given resistor for the corresponding values of potential difference V across the resistor are given below:

Plot a graph between V and I and calculate the resistance of that resistor.
Answer:

Question 8:
When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.
Answer:

Question 9:
A battery of 9 V is connected in series with resistors of 0.2 Ω, 0.3 Ω, 0.4 Ω, 0.5 Ω and 12 Ω, respectively. How much current would flow through the 12 Ω resistor?
Answer:
Since all the resistors are in series, the same current, 0.67 A flows through the 12 Ω resistor.

Question 10:
How many 176 Ω resistors (in parallel) are required to carry 5 A on a 220 V line?
Answer:

Question 11:
Show how you would connect three resistors, each of resistance 6 Ω , so that the combination has a resistance of (i) 9 Ω , (it) 4 Ω .
Answer:
(i) When two 6 Ω resistances are in parallel and the third is in combination to this, the equivalent resistance will be 9 Ω.

(ii) When two 6 Ω resistances are in series and the third is in parallel to them, then it will be 4 Ω.

Question 12:
Several electric bulbs designed to be used on a 220 V electric supply line, are rated 10 W. How many lamps can be connected in parallel with each other across the two wires of 220 V line if the maximum allowable current is 5 A?
Answer:
Since, N bulbs of power P each connected in parallel will make the total power of NP,

Question 13:
A hot plate of an electric oven connected to 220 V line has two resistance coils A and B, each of 24 Q resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?
Answer:

Question 14:
Compare the power used in the 2 Ω resistor in each of the following circuits.
(i) a 6 V battery in series with 1 Ω and 2 Ω resistors, and
(ii) a 4 V battery in parallel with 12 Ω and 2 Ω resistors.
Answer:

Question 15:
Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to electric mains supply. What current is drawn from the line if the supply voltage is 220 V?
Answer:

Question 16:
Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?
Answer:
Energy consumed by 250 W TV set in 1 h = 250 x 1 = 250 Wh.
Energy consumed by 1200 W toaster in 10 min = 1200 X 1/6 = 200 Wh.
∴ Energy consumed by TV set is more than the energy consumed by toaster in the given timings.

Question 17:
An electric heater of resistance 8 f2 draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.
Answer:

Question 18:
Explain the following.
(a) Why is the tungsten used almost exclusively for filament of electric lamps?
(b) Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
(c) Why is the series arrangement not used for domestic circuits?
(d) How does the resistance of a wire vary with its area of cross-section?
(e) Why are copper and aluminum wires usually employed for electricity transmission?
Answer:
(a) It has high melting point and emits light at a high temperature.
(b) It has more resistivity and less temperature coefficient of resistance.
(c) (i) All appliances do not get same potential in series arrangement.
(ii) All appliances cannot be individually operated.
(d) R ∝ =1 / Area of cross – section.
(e) They are very good conductors of electricity.

Short Answer Type Questions

Question 1:
Three 2 Ω resistors, A, B and C are connected as shown in figure. Each of them dissipates energy and can withstand a maximum power of 18 W without melting. Find the maximum current that can flow through the three resistors.
Answer:

Question 2:
Should the resistance of an ammeter be low or high? Give reason.
Answer:
The resistance of an ammeter should be low so that it will not disturb the magnitude of current flowing through the circuit when connected in series in a circuit.

Question 3:
How does use of a fuse wire protect electrical appliances?
Answer:
The fuse wire is always connected in series with the live wire or electrical devices. If the flow of current exceeds the specified preset value due to some reason, the heat produced melts it and disconnects the circuit or the device from the mains. In this way, fuse wire protects the electrical appliances.

Question 4:
What is electrical resistivity? In a series electrical circuit comprising a resistor made up of a metallic wire, the ammeter reads 5 A. The reading of the ammeter decreases to half when the length of the wire is doubled. Why?
Answer:
The resistance offered by a metallic wire of unit length and unit cross-sectional area is called electrical resistivity.

Hence, when the length of wire is doubled, the resistance becomes double and current decreases to half.

Question 5:
A current of 1 ampere flows in a series circuit containing an electric lamp and a conductor of 5 Ω when connected to a 10 V battery. Calculate the resistance of the electric lamp.
Now if a resistance of 10 Ω is connected in parallel with this series combination, what change (if any) in current flowing through 5 Ω conductor and potential difference across the lamp will take place? Give reason.
Answer:

Question 6:
Why is parallel arrangement used in domestic wiring?
Answer:
Parallel arrangement is used in domestic wiring because
(i) Each appliance gets the same voltage as that of the mains supply.
(ii) If one component is switched off, others can work properly.
(iii) Fault in any branch of the circuit can be easily identified.

Question 7:
B_1, B₂ and B₃ are three identical bulbs connected as shown in figure. When all the three bulbs glow, a current of 3A is recorded by the ammeter A.

(i) What happens to the glow of the other two bulbs when the bulb B j gets fused?
(ii) What happens to the reading of A₁ ,A₂ , A₃ and A when the bulb B₂ gets fused?
(iii) How much power is dissipated in the circuit when all the three bulbs glow together?
Answer:
(i) Since B₁ ,B₂ and B₃ are in parallel, the potential difference across each of them will remain same. So when the bulb B₁ gets fused, B₂ and B₃ have the same potential and continues with the same energy dissipated per second, i.e. they will glow continuously as they were glowing before.

Long Answer Type Questions

Question 8:
Three incandescent bulbs of 100 W each are connected in series in an electric circuit. In another circuit, another set of three bulbs of the same wattage are connected in parallel to the same source.
(а) Will the bulb in the two circuits glow with the same brightness? Justify your answer.
(b) Now let one bulb in both the circuits get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason.
Answer:

(a) The bulbs in the two circuits will not glow equally bright as the current through them is not the same.

(b) As one bulb fuses, the other bulbs in the series circuit will not glow because the circuit becomes an open circuit. While the rest of bulbs in parallel circuit will continue to glow without getting disturbed because in parallel combination, current gets additional paths to flow.

Question 9:
Find out the following in the electric circuit given in figure:


Answer:

(e) No difference, since the ammeters are connected in series and same current will pass through them, so reading of both ammeters will be same.

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Periodic Classification of Clements – CBSE Notes for Class 10 Science

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1. Need for classification of elements:
Increase in discovery of different elements, made it difficult to organise all that was known about the elements. To study the large number of elements with ease, various attempts were made. The attempts resulted in classification of elements into metals and non-metals.

2. Dobereiner’s triads: –
Johann Wolfgang Dobereiner, a German chemist, classified the known elements in groups of three elements on the basis of similarities in their properties. These groups were called triads.
(i) Characteristics of Triads:
(a) Properties of elements in each triad were similar.
(b) Atomic mass of the middle element was roughly the average of the atomic masses of the other two elements.
(ii) Examples of Triads:

(iii) Limitations: Dobereiner could identify only three triads. He was not able to prepare triads of all the known elements.

3. Newlands’ Law of Octaves:
John Newlands’, an English scientist, arranged the known elements in the order of increasing atomic masses and called it the ‘Law of Octaves’. It is known as ‘Newlands’ Law of Octaves’.
(i) Characteristics of Newlands’ Law of Octaves:
(a) It contained the elements from hydrogen to thorium.
(b) Properties of every eighth element was similar to that of the first element.
(ii) Table showing Newlands’ Octaves:

(iii) Limitations of Newlands’ law of Octaves:
(a) The law was applicable to elements up to calcium (Ca).
(b) It contained only 56 elements.
(c) In order to fit elements into the table, Newlands’ adjusted two elements like cobalt and nickel in die same slot and also put some unlike elements under same note.

4. Mendeleev’s Periodic Table : Dmitri Ivanovich – 5 ’ Mendeleev, a Russian demist, was the most important contributor to the early development of a periodic table of elements wherein the elements were arranged on the basis of their atomic mass and chemical properties.
(i) Characteristics of Mendeleev’s Periodic Table:
(a) Mendeleev arranged all the 63 known elements in an increasing order of their atomic masses.
(b) The table contained vertical columns called ‘groups’ and horizontal rows called ‘periods’.
(c) The elements with similar physical and chemical properties came under same groups.
(ii) Mendeleev’s Periodic Law : The properties of elements are the periodic function of their atomic masses.
(iii) Achievements of Mendeleev’s Periodic Table:
(a) Through this table, it was very easy to study the physical and chemical properties of various elements.
(b) Mendeleev adjusted few elements with a slightly greater atomic mass before the elements with slightly lower atomic mass, so that elements with similar properties could be grouped together. For example, aluminium appeared before silicon, cobalt appeared before nickel.
(c) Mendeleev left some gaps in his periodic table.
He predicted the existence of some elements that had not been discovered at that time. His predictions were quite true as elements like scandium, gallium and germanium were discovered later.
(d) The gases like helium, neon and argon, which were discovered later, were placed in a new group without disturbing the existing order.
(iv) Limitations: 
(a) No fixed positions was given to hydrogen in the Mendeleev’s periodic table.
(b) Positions of Isotopes of all elements was not certain according to Mendeleev’s periodic table.
(c) Atomic masses did not increase in a regular manner in going from one element to the next.

5. Modem Periodic Table: Henry Moseley, gave a new ! property of elements, ‘atomic number’ and this was I adopted as the basis of Modem Periodic Table.
(i) Modem Periodic Law: Properties of elements are a periodic function of i their atomic number.
(ii) Position of elements in Modem Periodic Table:
(a) The modem periodic table consists of 18 groups and 7 periods.
(b) Elements present in any one group have the same number of valence electrons. Also, the number of shells increases as we go down the group.
(c) Elements present in any one period, contain the same number of shells. Also, with increase in atomic number by one unit on moving from left to right, the valence shell electrons increases by one unit.
(d) Each period marks a new electronic shell getting filled.
(iii) Table showing Electronic Configuration of First 20 Elements:

Trends in the Modern Periodic Table:
(i) Valency: Valency of an element is determined by the number of valence electrons present in the outermost shell of its atom.
• Valency of elements in a particular group is same.
• Valency of elements in a period first increases from one to four and then decreases to zero.
(ii) Atomic Size: Atomic size refers to the radius of an atom.
In a period, atomic size and radii decreases from left to right.
In a group, atomic size and radii increases from top to bottom.
(iii) Metallic and Non-metallic Properties:
(a) The tendency to lose electrons from the outermost shell of an atom, is called metallic character of an element.
(b) The tendency to gain electrons from the outermost shell of an atom, is called non-metallic character of an element.

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Light Reflection and Refraction – CBSE Notes for Class 10 Science

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1. Light travels in a straight line.

2. Light gets reflected when it falls on polished surfaces; like mirrors.

3. Light suffers refraction when it travels from one medium to another.

4. There is a change in the wavelengths!light when it moves from one medium into another.

5. The bouncing back of light when it strikes a smooth or polished surface is called reflection of light. Reflection is of two types; Specular or regular and Diffuse or irregular reflection.

6. The angle of incidence is equal to the angle of reflection. Mathematically, we have ∠i = ∠r.

7. The image is as far behind the mirror as the object is in front.

8. The image is unmagnified, virtual and erect.

9. The image has right-left reversal.

10. Focal length of a plane mirror is infinity.

11. Power of a plane mirror is zero.

12. If a plane mirror is turned by an angle, the reflected ray turns by 2θ.

13. The least size of a plane mirror to view an object is equal to half the size of the object.

14. Pole (Vertex): The central point of a mirror is called its pole.

15. Centre of curvature : The centre of the sphere of which the mirror is a part is called the centre of curvature. It is denoted by C.

16. Radius of curvature : The radius of the sphere of which the mirror is a part is called the radius of curvature. It is denoted by R.

17. Principal axis : The straight line passing through the pole and the centre of curvature of the mirror is called the principal axis.

18. Principal focus : It is a point on the principal axis at which the rays parallel to the principal axis meet after reflection or seem to come from. For a concave mirror, the focus lies in front of the mirror and for a convex mirror, it lies behind the mirror. In short, a concave mirror has a real focus while aconvex mirror has a virtual focus.

19. Focal plane : A plane, drawn perpendicular to the principal axis and passing through the principal focus.

20. Focal length : The distance between the pole and the focus is called the focal length. It is represented by f. The focal length is half the radius of curvature.

21. Aperture: The size of the mirror is called its aperture. It is also defined as the effective diameter of the light reflecting area of the mirror.

22. Real image : When the rays of light, after reflection from a mirror, actually meet at a point, then the image formed by these rays is said to be real. Real images can be obtained on a screen.

23. Virtual image: When the rays of light, after reflection from a mirror, appear to meet at a point, then the image formed by these rays is said to be virtual. Virtual images can’t be obtained on a screen.

24. The following rays are used while drawing ray diagrams to find the position of an image :

1. A ray of light parallel to the principal axis after reflection passes through the focus. (1)
2. A ray of light passing through the focus after reflection becomes parallel to the principal axis. (2)
3. A ray of light incident on the centre of curvature retraces its path after reflection form the mirror.
   

25. For mirrors, the following results hold :
u is – ve, if the object is in front of the mirror.
(Real object)
u is + ve, if the object is behind the mirror.
(Virtual object)
v is – ve, if the image is in front of the mirror.
(Real image)
vis +ve, if the image is behind the mirror.
(Virtual image)
Focal length of a concave mirror is taken as – ve. Focal length of a convex mirror is taken as +ve.

26. When the image formed by a spherical mirror is real, it is also inverted and is on the same side of the mirror as the object. Since both v and u are negative, the magnification is negative.

27. When the image formed by a spherical mirror is virtual, it is also erect and is on the other side of the mirror as the object. In this case, u is – ve and v is + ve , therefore, m is positive.

28. The expression for the mirror formula is 1/u+1/v = 1/f

29. Linear magnification is given by the expression

30. If m is positive, the image is erect w.r.t the object and if m is negative, the image is inverted w.r.t. the object.

31.The position of the image for various positions of the object for a concave mirror is as shown in the table below. The table also shows the use of the mirror for different positions of the object.

The position of the image for various positions of the object for a convex mirror is as shown in the table below. The table also shows the use of the mirror for different positions of the object.

32. The bending of light when it travels from one medium into another is called refraction of light

33.

34. As light travels from ,one medium to another, the frequency of light does not change.

35. Light refracts because it has different speeds in different media.

36. The refraction of light obeys the following two laws :

1. The incident ray, the refracted ray and the normal at the point of incidence all lie in the same plane.
2. The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant.This
   constant is called the index of refraction or refractive index.
   

37. If _wn_g is the refractive index of glass w.r.t. water, _an_g  be the refractive index of glass w.r.t. air and _an_w  be the refractive index of water w.r.t. air ,then

38. The most familiar and widely used optical device is the lens. A lens is an optical system with two refracting surfaces. The simplest lens has two spherical surfaces close enough together that we can neglect the distance between them. Such a lens is called a thin lens. The two common types of lenses are Converging lens or Convex lens, Diverging lens or Concave lens.

39. It should be noted that, if the above lenses are surrounded by .a material with a refractive index greater than that of the lens, the convex lens gets converted into a concave lens and vice-versa.

40. Any lens that is thicker at its centre than at its edges is a converging lens with positive f, and any lens that is thicker at its edges than at the centre is a diverging lens with negative f.

41. Optical centre : The central point C in the lens is called the optical centre. If a ray is incident towards the optical centre, it passes undeviated .through the lens.

42.Principal axis: Since the lens contains two spherical surfaces, therefore, it has two centres of curvatures.
The line joining these centres and passing through the optical centre is called principal axis.

43. Aperture: The effective width of a lens through which refraction takes place is called the aperture.

44. Focus and Focal Length : If a beam of light moving parallel to the principal axis of a convex lens is incident on it, the rays converge or meet at a point on the principal axis. This point F is called the focus. The distance CF is called the focal length. If a beam of light moving parallel to the principal axis is incident on a concave lens, the beam of light diverges. If these diverged rays are produced backward, they meet at a point F on the principal . axis. The transmitted rays appear to come from this point. This point F is called the focus and distance CF is called the focal length.

45. For drawing the ray diagrams, we note the following :

1. All rays parallel to the principal axis after refraction pass through the principal focus or seem to come from it.
2. A ray of light passing through the focus after refraction becomes parallel to the principal axis.
3. A ray of light passing through the optical centre of the lens after refraction passes undeviated.

46. A convex and a concave lens can be supposed to be made-up of prisms.

47. Image formation by a concave lens.

48. Image formation by a convex lens.

49. New Cartesian sign conventions :

1. All distances, object distance (u), image distance (v) and focal length f are measured from the optical centre.
2. The distances measured in the direction of incident ray are taken as positive and distances measured against the direction of incident ray are taken as negative.
3. All distances (heights) of objects and images above principal axis are taken as positive and those below the principal axis are taken as negative.

50. For the two lenses, the sign conventions take the form

1. u is- ve, if the object is in front of the lens. (Real object)
2. u is +ve, if the object is virtual.
3. v is – ve, if the image is on the same side as that of the object. (Virtual image )
4. v is +ve, if the image is real.
5. Focal length of a concave lens is taken as – ve.
6. Focal length of a convex lens is taken as +ve.

51. Lens formula for convex lens 1/v-1/u = 1/f

52. The linear magnification produced by a lens is defined as the ratio of the size of the image (h’) to the size of the object (h). It is represented by m i.e.,

53. If the magnification of a lens is negative, then the image formed is inverted and real.

54. If the magnification of a lens is positive, then the image formed is erect and virtual.

55. Power is defined as the reciprocal of the focal length. Power is measured in dioptre.

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Heredity and Evolution – CBSE Notes for Class 10 Science

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1. Heredity : It refers to the transmission of characters or traits from the parents to their offspring. Heredity is the continuity of features from one generation to another which are present in fertilised egg or zygote. The zygote develops into an organism of a particular type only.

2. Genetics : It is the branch of biology which deals with heredity and variation. Genetics is to help our understanding of heredity by knowing how offspring inherit characteristics from their parents.

3. Variation : It means the differences in the characters or traits among the individuals of a species. Variations occur during reproduction both because of error in DNA copying and as a result of sexual reproduction. Variations contribute to evolution.
Causes of variations:

1. Different combinations of genetic material.
2. Some positive gene mutations.
3. Interaction of genes with environmental changes (adaptations).

Importance of variations:

1. It forms, the. basis of heredity.
2. It causes adaptations due to which organism can easily adjust to its changing environment.
3. Accumulation of variations forms the basis of evolution.

Remember!
Variations are produced both in sexual and asexual reproduction but amount of variations produced in asexual reproduction are subtle (so little) that they are hardly noticeable as compared to variations caused due to sexual reproduction.

4. Genotype : The genetic constitution of an organism e.g., Genotype of human male is 44 + XY and
genotype of human female is 44 + XX

5. Phenotype : The appearance of the organism, i.e., the way in which genotype is expressed. Phenotype is the result of interaction of genes with the environment.
e.g., Red colour may be controlled by a pair of genes RR. Now if genotype is RR phenotype will be red only but if genotype is Rr then also phenotype will be red since R is a dominant gene.

6. Gene : It is the basic unit of inheritance by which characters are transferred from parents to their offspring. Gene consists of a specific length of DNA on a chromosome. A specific Segment of DNA that provides the information for one protein is called gene for that protein.
According to Mendel, both parents must contribute equally to the DNA of the progeny during sexual reproduction. As both parents determine the trait in the progeny, so both parents must be contributing a copy of the same gene.

7. Chromosomes : These are the long threads present in the nucleus of every cell. Chromosomes are made- up of DNA and protein. Each chromosome contains very long molecule of DNA.
Remember!
Each gene set is present as separate independent pieces each called a chromosome. Each cell have two copies of each chromosome, one each from male and female parents. Every germ cell will take one chromosome from each pair and these may be of either maternal or paternal origin. When two germ cells combine, they will restore the normal number of chromosomes in the progeny, ensuring the stability of the DNA of the species. Such mechanism of inheritance is used by all sexually and asexually reproducing organisms.

8. Allele : It is a alternative form of a gene occupying the same position on a chromosome and affecting the same characteristic but in two alternative ways, e.g., the free and attached ear lobe are the alleles of ear lobe character.
Expressing allele of a gene :

1. Homozygous dominant in capital letters, e.g., tallness(TT)
2. Homozygous recessive in smalMetters, e.g., shortness or dwarfness (tt)
3. Heterozygous (Tt)-lt will be called hybrid tall.

9. Dominant allele: An allele that affects the phenotype of an organism both in heterozygous and homozygous condition. It is denoted by a capital letter, e.g., tallness in pea plant is denoted by ‘T.

10. Recessive allele: An allele that affects the phenotype of the organism in absence of a dominant allele, i.e., in homozygous recessive individuals. It is denoted by a small alphabet, e.g., dwarfness in pea plant is denoted by’t’.

11. Homozygous: When both alleles of a particular gene are the same, e.g., TT

12. Heterozygous : When both alleles of a particular gene are different, e.g., Tt

13. Diploid : Cells or organism containing two sets of genes, e.g., human body cells. Diploid cells have genetic constitution of 2n.

14. Haploid : Cells or organism containing one set of genes, e.g., human reproductive cells (sperms and ova). Haploid cells have genetic constitution of n.

15. Monohybrid cross : A cross between two parents taking the alternative traits of one single character, e.g., A cross between tall and dwarf pea plants.
Monohybrid Ratio :

1. In F₁ generation : 100% hybrid
2. In F₂ generation : phenotypic ratio is 3 : 1 and genotypic ratio is 1 : 2 : 1

16. Dihybrid cross: A cross between two parents taking into consideration alternative traits of two different characters, e.g., A cross between two pea plants one having round, green seeds and the other having wrinkled, yellow seeds.
Dihybrid Ratio :

1. F₁ ratio is 100% Hybrid type.
2. F₂ ratio : Phenotypic is 9 : 3 : 3 : 1 and Genotypic . ratio is very complex.

17. Human Blood Groups: There are four types of blood groups A, B, AB or O. These are controlled by a gene which is denoted by symbols I^A, I^B and I^O (sometimes also denoted as i). The genes I^A and I^B show no dominance over each other (they are codominant, i.e., both expresses themselves independently). But these both genes are dominant over the gene I^O. Therefore, blood group of a person depends on the type of genes present, e.g., (i) Blood group A has the following gene types :

18. Determining sex of a newborn individual genetically:
(a) In human beings the sex of the individual is ” determined genetically.
(b) There are 23 pairs of chromosomes of which 22 are similar in male and female and are known as autosomes.
(c) The remaining one is sex chromosome which is XY in males and XX in females.
(d) Males produce two types of sperms X and Y, while female produces one type of egg X.
(e) If a X type of sperm fertilizers the egg then the sex of baby will be female (XX).
(f) If Y type of sperm fertilizers the egg then the sex of the baby will be male (XY).

19. Mendel’s experiment to show that traits may be dominant or recessive:
(a) Mendel conducted breeding experiments in garden pea.
(b) selected pure plant of a tall/short plant.
(c) produced first generation plants by crossing them.
(d) found that all plants were tall.
(e) produced second generation by self fertilization of hybrids.
(f) found that three quarter of the plants were tall and one quarter was short.

20. Homologous chromosomes: A pair of corresponding chromosomes of the same shape and size, one from each parent.

21. Autosomes and Sex chromosomes : The identical » chromosome pairs are called autosomes. The
chromosome pair which is different are called sex chromosomes. Humans have 23 pairs of chromosomes. 1-22 pairs are autosomes while 23rd pair (XX in females and XY in males) which are designated as X and Y are sex chromosomes.

22. Molecular Phylogeny: It is the study of evolutionary relationships by comparing DNA of different species.

23. Natural selection : Natural selection is one of the basic mechanisms of evolution, along with mutation, migration and genetic drift. Natural selection means the environmental conditions prevailing around an organism against which organism adapts itself, grows – and reproduces further. This leads to a change in the composition of genes within a population further causing evolution. Thus, it can be said that,
Natural selection results in adaptation in population to fit their environment better. Thus, natural selection direct evolution in the population of a particular species.

24. Fossils of the information which they provide regarding evolution: Fossils are the remains of ancient life forms, which got preserved somehow in the layers of earth, snow or oil.
Information given by fossils:

1. They reveal that the life forms which existed earlier do not exist today
   which indicate that the living forms are ever changing (evolving).
2. They are used to guess the time when a particular organism existed on earth. It is done through carbon dating.

25. Genetic drift: The change in the frequency of some genes in a population which provides diversity without any survival advantage is called genetic drift.

26. The various ways in which individuals with a particular trait may increase in a population : Differences in population are responsible for the diversity such as, colour of eyes, hair, shape of ear lobes. This occurs due to : (i) Sexual reproduction (ii) Inaccuracies during DNA replication (iii) Due to environmental changes. This diversity will increase with time as these variations can be passed on only through DNA/genes during reproduction through reproductive tissue (germ cells or gametes).
(i) If these variations give survival advantage, then such traits are selected in nature and such traits increase in a population.
(ii) Due to genetic drift. This occurs due to geographical or reproductive isolation. It results in the change in gene frequency in a particular : population.
(iii) Migration which leads to gene flow in and out of the population.
(v) Mutation caused due to particular type of environment. ,
(v) Acquired traits due to particular type of environment.

27.Evidence of evolution : Errors in DNA copying (mutation) and sexual reproduction lead to variations which form the basis of evolution. Characteristics that
are common in different kinds of living organisms provide evidence in favour of evolution.

28.Evolution : Evolution can be defined as a naturally occurring slow, continuous and irreversible process of change. The gradual change of living organisms from pre-existing organisms since the beginning of life is called organic evolution. Whereas, gradual change in elements from one form to another with time is termed as inorganic evolution, i.

29.Inherited traits : are those traits which are passed from one generation to another through specific genes. Any change in DNA of the germ cells will be passed.
30. Acquired traits : are those traits which are acquired by the organism in its lifetime, e.g., removal of tail cannot change the genes of the germ cells of the mice thus cannot be passed to next generation.

31. Speciation : It means the origin of new species from the existing ones. It happens when different populations of the same species evolve along different lines.
How speciation occurs ?

1. It occurs when two populations are isolated (both geographically and reproductively) leading to almost no gene flow between the two populations.
2. Over generations, genetic drift will accumulate different changes in each sub-population.
3. Natural selection may also operate differently in these different locations.
4. Together natural selection and genetic drift will cause such changes (severe changes in the DNA) that these two groups will not be able to reproduce with each other even if they happen to meet.
5. When DNA changes occur to larger extent, it may lead to change in the number of chromosomes or gene expression, eventually the germ cells of the two groups cannot fuse with each other. This leads to emergence of new species.

32. Estimating Age of Fossil: There are 2 methods :

1. Relative method : On digging, the fossils which are closer to the surface are more recent than the fossils found in deeper layers.
2. Dating fossils (carbon dating method): It is done by detecting the ratios of different isotopes of the same element (i.e., isotope of C-14 which is radioactive) in the fossil material.

33. Evolution by stages :

1. Complex organs like eye has evolved from rudimentary organs, (e.g., rudimentary eye in flatworm might be useful enough to give only a fitness advantage and the structure of eye in different organisms is different indicating them to have different evolutionary origins) not by a single DNA change but created bit-by-bit over generations.
2. A change that is useful for one property to start with can become useful later for quite a different
   function (e.g., Feathers might start as providing insulation in cold weather. But later, they might be useful for flight. Some heavy birds and reptiles also have feathers but they do not fly.
3.  Some very dissimilar looking structures evolve from a common ancestral design, e.g., wild cabbage was cultivated as a food plant and many different vegetables were generated by selection over last two thousand years, (a) Selection of very small distances between the leaves gave rise to cabbage we eat. (b) Selection for arrested flower development gave rise to broccoli, (c) Selection for sterile flowers gave rise to cauliflower (d) Selection for swollen parts gave rise to kohlrabi.(e) Selection for larger leaves gave rise to leafy vegetable kale. It suggests that, if these selections were not done then there would have been only wild cabbage.

34. Homologous organs are organs having same origin and basic structure but they appear different and perform different functions in various organisms, e.g., (a) Fore limbs of horse and arms of man.
(b) Wings of birds and flippers of whale.
Similarities in basic structure of (homologous) organs in different organisms, indifferent groups indicate common ancestry.

35. Analogous organs are organs, which look similar because they perform same function, but they do not have same origin and basic structure.
e.g.,(a) Wings of birds and wings of insects. (b) Fins of fish and flippers of whale.

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Our  Environment Chapter Wise Important Questions Class 10 Science

SHORT ANSWER TYPE QUESTION[II] [3 Marks] – Year 2007

1. (a) What is ‘environmental pollution’?
(b) Distinguish between biodegradable and non-biodegradable pollutants.
(c) Choose the biodegradable pollutants from the list given below:
Sewage, DDT, radioactive waste, agricultural waste. [Delhi]
Answer. (a) Environmental pollution is an undesirable change in the physical, chemical or biological
characteristics of the natural environment, brought about by man’s activities. This pollution may affect the soil, rivers, seas or the atmosphere.

(c) Biodegradable pollutants are sewage and agricultural waste.

VERY SHORT ANSWER TYPE QUESTIONS [1 Mark] – Year 2008

2. How is the increase in demand for energy affecting our environment adversely?
Answer. The increase in demand for energy affects our environment adversely. Due to this increase, pollutants like CO,C0₂ , S0₂, etc., are released in to the atmosphere which leads to greenhouse effect.

3. Why is ozone layer getting depleted at the higher levels of the atmosphere? [Delhi (C)]
Answer. Ozone layer is getting depleted at the higher levels of the atmosphere due to effect of chlorofluorocarbons (CFC_s) which are used as refrigerants and in fire extinguishers.

4. Name any two abiotic components of an environment. [Delhi (C)]
Answer. Two abiotic components of an environment are temperature and rainfall.

SHORT ANSWER TYPE QUESTION[II] [3 Marks] – Year 2008

5. Why are bacteria and fungi called decomposers? List any two advantages of decomposers to the environment. [Delhi]
Answer. Bacteria and fungi breakdown the dead remains and waste products of organisms. These micro organisms are called the decomposers as they breakdown the complex organic substances into simple inorganic substances that go into the soil and are used up once more by the plants.
Two advantages of decomposers to the environment are as follows:

1. Decomposers feed, on the dead bodies of plants and animals. They return the simple components to soil and help in making the steady state of ecosystem by recycling of nutrients. They, therefore, create a balance in the environment.
2. They also act as scavengers or cleansing agents of the atmosphere.

VERY SHORT ANSWER TYPE QUESTIONS [1 Mark] – Year 2009

6. What are the two main components of our environment? [Delhi]
Answer. The two main components of our environment are the biotic or living components and abiotic or non-living components.

7. Why are green plants called ‘producers’? [All India]
Answer. Green plants are called ‘producers’ because they can produce food by photosynthesis in the presence of sunlight.

8. Which disease is caused in human beings due to depletion of ozone layer in the atmosphere? [Foreign]
Answer. Skin cancer is caused in human beings due to the depletion of ozone layer in the atmosphere.

SHORT ANSWER TYPE QUESTIONS [II] [2 Marks] – Year 2009

9. How is ozone formed in the upper atmosphere? Why is the damage of ozone layer a cause of concern to us? State a cause of this damage. [Delhi(C)]
Answer. Ozone is formed in upper atmosphere by the reaction of ultraviolet (UV) radiations on oxygen (0₂) molecule.
The damage to ozone layer is a cause of concern to us as due to its damage, more ultraviolet rays reach the earth’s surface causing various health hazards.

A cause of this damage is the presence of large amount of chlorofluorocarbons in the atmosphere.

10. State two problems caused by the non- biodegradable waste that we generate in our daily life. [All India (C)]
Answer. Two problems caused by non-biodegradable waste that we generate in our daily life are:

1. It clogs drains.
2. It causes water and soil pollution.

11. What are biodegradable and non- biodegradable substances? Select two biodegradable pollutants from the following: Agricultural waste, glass, plastic, sewage, DDT. [Ail India (C)]
Answer. Biodegradable substances are those substances which are broken down into simpler, harmless substances in nature in due course of time by the biological processes such as micro organisms like certain bacteria.
Non-biodegradable substances are those substances which cannot be broken down into simpler, harmless substances in nature.
Two biodegradable pollutants are agricultural waste and sewage.

SHORT ANSWER TYPE QUESTIONS [I] [2 Marks] – Year 2010

12. Construct an aquatic food chain showing four trophic levels. [All India]
Answer. Food chain in aquatic ecosystem:

13. Explain ‘biological magnification’ with the help of an example. [All India]
Answer. Pesticides used in crops are washed down .into the soil. From soil these are absorbed by plants along with water and minerals and thus, they enter the food chain. While consuming the crops, human beings also consume these pesticides which get accumulated in our bodies. This phenomenon is known as biological magnification.

14. Describe how decomposers facilitate recycling of matter in order to maintain balance in the ecosystem. [Foreign]
Answer. Decomposers are micro organisms that obtain energy from the chemical breakdown of dead organisms of animals or plants. These micro organisms breakdown the complex organic substances of dead organisms into simple inorganic substances that go into the soil and are used up once more by the plants. Decomposers thus, help in recycling of matter.

15. Explain the phenomenon of “biological magnification” How does it affect organisms belonging to different trophic levels particularly the tertiary consumers? [Delhi]
Answer. The process in which harmful chemicals enter a food chain and get accumulated progressively at each trophic level is called biological magnification.
Harmful and toxic chemicals enter our bodies when they are added to soil and water. Use of pesticides to protect the food crops from diseases and pests and chemical wastes of factories are dumped in open or disposed off into rivers. These chemicals are washed down into the soil and ultimately to water table or get absorbed or taken up from the soil by the plants along with water and minerals and in this way harmful chemicals enter the food chain. The quantity of these harmful chemicals increase with increase in trophic level of the food chain because these substances are not degradable. Man is at the top of the food chain, so concentration is maximum in human beings.
Thus, accumulation of DDT has been maximum in man as DDT is used to destroy pests. DDT is accumulated in the following way in this food chain:
This is the reason why our food grains such as wheat and rice, vegetables and fruits and even meat contain varying amounts of pesticides residues. So, the highest trophic level at the extreme right of food chain has the maximum concentration of harmful chemicals in a food chain.

16. “Damage to the ozone layer is a cause for concern.” Justify this statement. Suggest any two steps to limit this damage. ‘ [Delhi]
Answer. Ozone layer prevents the harmful ultraviolet radiation to enter the atmosphere and reach the earth’s surface. Depletion of ozone layer has become a cause for concern because it can cause serious effects on human body and other organisms of the environment like fatal diseases such as skin cancer, changes in genetic material DNA, eye damage, etc.
Two steps to limit this damage are as follows:

1. Judicious use of aerosol spray propellants such as fluorocarbon and chlorofluorocarbons which cause depletion or hole in ozone layer.
2.  Control over large scale nuclear explosions and limited use of supersonic planes.

VERY SHORT ANSWER TYPE QUESTIONS [1 Mark] – Year 2011

17. What will happen if we kill all the organisms in one trophic level? [Delhi]
Answer. If we kill all the organisms in one trophic level, the following effects will take place:

1. The population of organisms in previous trophi’c level will increase.
2. The organisms in next trophic level will not be able to get the food, so they will migrate to some other ecosystem or die.
3. It will cause an ecological imbalance in the food chain.

18. Why did United Nations act to control the production of chlorofluorocarbons (CFC_s) used in refrigerators? [Delhi]
Answer. CFC_s deplete the ozone layer around the earth, hence their production is controlled by United Nations.

19. Which compounds are responsible for the depletion of ozone layer? [Delhi]
Answer. The compounds responsible for the depletion of ozone layer are chlorofluorocarbons (CFCs).

20. Define ‘trophic level’. [Delhi]
Answer. Trophic level is the position that an organism occupies in a food chain, where transfer of food or energy takes place.

21. What are the various steps in a food chain called? [Delhi]
Answer. The various steps in a food chain are called trophic levels.

22. What is the important function of presence of ozone in earth’s atmosphere? [Delhi]
Answer. The important function of presence of ozone in earth’s atmosphere is that it shields the surface of the earth from ultraviolet (UV) radiations of the sun.

23. Give an example to illustrate that indiscriminate use of pesticides may result-in the degradation of the environment. [All India]
Answer. The pesticides used in crop field are washed down into the water bodies. From water bodies, these are absorbed by aquatic plants and animals of a food chain and thereby degrades the environment.

24. Why is it necessary to conserve our environment? [All India]
Answer. It is necessary to conserve our environment to prevent depletion of natural resources and environmental damage, thereby sustaining life.

25. What is meant by a biodegradable waste? [All India]
Answer. Biodegradable wastes are those substances which are broken down into simpler, harmless substances in nature in due course of time by the biological processes such as action of micro organisms like certain bacteria.
Examples: Urine and faecal matter, sewage, agricultural residue, paper, wood, cloth and cattle dung.

26. What is the role of decomposers in the ecosystem? [Foreign]
Answer. Role of decomposers in the environment:

1. They return the nutrients to the nutrient pool.
2. They help in completing the different bio-geochemical cycles, thus they maintain the balance in the ecosystem.

27. What step is being taken to limit the damage to the ozone layer? [Foreign]
Answer.

1. Judicious use of aerosol spray propellants such as fluorocarbon and chlorofluorocarbons which cause depletion or hole in ozone layer.
2. Control over large scale nuclear explosions and limited use of supersonic planes.

28. Why are some substances non- biodegradable? [Foreign]
Answer. Some substances are non-biodegradable because they cannot be broken down into simpler harmless substances in nature.

29. Which class of chemicals is linked to the decrease in the amount of ozone in the upper atmosphere of the earth? [Delhi]
Answer. The chemical compound Chlorofluorocarbon is responsible for decrease of ozone in the upper atmosphere of the earth.

30. Name two decomposers operating in our ecosystem. [All India 2011; Delhi]
Answer. Bacteria and fungi.

31. Select two non-biodegradable substances from the following waste generated in a kitchen: spoilt food, paper bags, milk bags, vegetable peels, tin cans, used tea leaves. [Delhi]
Answer. Milk bags and tin cans.

32. What happens when higher energy ultraviolet radiations act on the oxygen at the higher level of the atmosphere? [All India]
Answer. When high energy ultraviolet radiations act on oxygen, ozone is produced:

33. In a food chain, 10,000 joules of energy is available to the producer. How much energy will be available to the secondary consumer to transfer it to the tertiary consumer? [All India ]
Answer. 10 J will be available to the secondary consumer to transfer to the tertiary consumer.

34. Write the name and formula of a molecule made up of three atoms of oxygen. [All India]
Answer. Ozone and its chemical formula is O₃.

35. List two man-made ecosystems. [All India]
Answer. Garden and Pond are man-made ecosystems.

36. Consider the following food chain which occurs in a forest: Grass -> Deer -> Lion
If 10000 J of solar energy is available to the grass, how much energy would be available to the deer to transfer it to the lion? [Foreign]
Answer. 10 J energy would be available to deer to transfer to lion.

37. Which of the following belong to the first trophic level of a food chain? Grass, Grasshopper, Plants, Rat, Tiger [Foreign]
Answer. Grass and plants belong to the 1st trophic level of a food chain.

38. Name the phenomenon in which non-biodegradable chemicals get accumulated progressively at each trophic level of a food chain. [Foreign]
Answer. Biological magnification.

Important QuestionsNCERT SolutionsSample PapersNCERT Exemplar Solutions

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Periodic Classification of Elements Chapter Wise Important Questions Class 10 Science

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SHORT ANSWER TYPE QUESTIONS [I] [2 Marks] – Year 2008

Question.1The elements of the second period of the Periodic Table are given below:
Li Be B C N O F
(a) Give reason to explain why atomic radii decrease from Li to F.
(b) Identify the most
(i) metallic and
(ii)non-metallic element.
Answer.
(a) It is because nuclear charge increases due to increase in atomic number, therefore, force of attraction between nucleus and valence electrons increases, i.e. effective nuclear charge increases, hence atomic radii decrease from Li to F.
(b) (i) Most metallic element is ‘Li’ as it
can lose electrons easily due to larger atomic size.
(ii) Most non-metallic element is ‘F’ because it can gain electrons easily due to smallest atomic size.

Question.2 The elements of the third period of the Periodic Table are given below:

(a) Which atom is bigger, Na or Mg? Why?
(6) Identify the most (i) metallic and (ii) non-metallic element in Period 3.
Answer. (a) Sodium is bigger than magnesium as it has lesser nuclear charge so there is less force of attraction between nucleus and valence electrons and less effective nuclear charge. It is, therefore, bigger in size.
(b) (i) Sodium is the most metallic as it can lose electrons easily due to its larger atomic size,
(ii) Chlorine is the most non-metallic element because it can gain electrons easily due to its smallest atomic size.

SHORT ANSWER TYPE QUESTIONS[II] [3 Marks] – Year 2008

Question.3 The position of three elements A, B and C in the Periodic Table is shown below:

Giving reasons, explain the following:
(a) Element A is a non-metal.
(b) Element B has a larger atomic size than element C.
(c) Element C has a valency of 1
Answer. (a) ‘A’ is non-metal because it can gain electron easily as it has 7 valence electrons and forms negative ion with stable electronic configuration.
(b) It is because ‘B’ has lesser atomic number, less nuclear charge, less force of attraction between valence electrons and nucleus therefore, has larger atomic size.
(c) ‘C’ has 7 valence electrons. It can gain one electron to become stable. So, its valency is equal to one.

Question.4 The position of three elements A, B and C in the Periodic Table is shown below:

Giving reasons, explain the following:
(a) Element A is non-metal.
(b) Atom of element C has a larger size ‘ than atom of element A.
(c) Element B has a valency of 1.
Answer. (a) It is because it has 7 valence electrons.
It can gain one electron to form negative ion. So, it is a non-metal.
(b)’C’ has more number of shells than A. So, it is larger in size.
(c)’B’ has one valence electron. It can lose one electron to become stable. So, its valency is equal to 1.

Question.5 What physical and chemical properties of elements were used by Mendeleev in creating his periodic table? List two observations which posed a challenge to Mendeleev’s Periodic Law.
Answer. Atomic mass as a physical property and nature and formulae of oxide and hydride formed, and chemical property was used by Mendeleev.
Following are the two observations which posed a challenge to Mendeleev’s Periodic Law.
(i) Increasing order of atomic weights could not be maintained while matching chemical properties. Chemical properties do not depend upon atomic mass.
(ii) Isotopes have different atomic mass but same chemical properties.

Question.6 Table given below shows a part of the Periodic Table.

(b) Atomic size of Mg is less than that of Na.
(c) Fluorine is more reactive than Chlorine.
Answer.
(a) They can lose electrons easily due to bigger size; energy required to remove electron is less.
(b) It is because of greater effective nuclear charge on Mg, i.e. more number of protons attract more number of electrons than Na.
(c) ‘F’ can form  F^– more easily than Cl due to smaller atomic size. F^– is more stable than Cl^–. Therefore, fluorine is more reactive than chlorine.

Question.7(a) Why do we classify elements?
(b) What were the two criteria used by Mendeleev in creating his Periodic Table?
(c) Why did Mendeleev leave some gaps in his Periodic Table?
(d) In Mendeleev’s Periodic Table, why was there no mention of Noble gases like Helium, Neon and Argon?
(e) Would you place the two isotopes ‘ of chlorine, CI-35 and CI-37 in
different slots because of their different atomic masses or in the same slot because their chemical properties are the same? Justify your answer.
Answer.
(a) It is done so as to study the properties of elements conveniently.
(b) Increasing order of atomic mass and similarities in chemical properties (especially nature and formulae of oxide and hydride formed).
(c) These gaps were left for undiscovered elements.
(d) Noble gases were not invented at that time.
(e) They will be kept at same slot as they have same chemical properties.

VERY SHORT ANSWER TYPE QUESTIONS [1 Mark] – Year 2009

Question.8 Lithium, sodium and potassium form a Dobereiner’s triad. The atomic masses of lithium and potassium are 7 and 39 respectively. Predict the atomic mass of sodium.
Answer.

Question.9 Chlorine, bromine and iodine form a Dobereiner’s triad. The atomic masses of chlorine and iodine are 35.5 and 126.9 respectively. Predict the atomic mass of bromine.
Answer.

Question.10 Why was the system of classification of elements into triads not found suitable?
Answer. It is because all the elements discovered at that time could not be classified into triads.

SHORT ANSWER TYPE QUESTIONSP [2 Marks] – Year 2009

Question.11 State Mendeleev’s periodic law. Write two achievements of Mendeleev’s periodic table
Answer. Mendeleev’s Periodic Law: ‘Properties of elements are the periodic function of their atomic masses.
Achievements:

1.  It could classify all the elements discovered at that time.
2. It helped in discovery of new elements.
3.  It helped in correction of atomic mass of somd of the elements.

SHORT ANSWER TYPE QUESTIONS[II] [3 Marks] – Year 2009

Question.12 (a) What is meant by periodicity
in properties of elements with reference to the periodic table?
(b) Why do all the elements of the same group have similar properties?
(c) How will the tendency to gain electrons change as we go from left to right across a period? Why?
Answer.
(a) The repetition of same properties after definite interval is called periodicity in properties.
(b) It is because they have same valence electrons therefore, have similar properties.
(c) Tendency to gain electrons increases from left to right in a period because atomic size goes on decreasing and effective nuclear charge increases.

Question.13 (a) What are ‘groups’ and ‘periods’ in the ‘periodic table’?
(b) Two elements M and N belong to group I and II respectively and are in the same period of the periodic table. How do the following properties of M and N vary?

1.  Sizes of their atoms
2.  Their metallic characters
3.  Their valencies in forming oxides
4.  Molecular formulae of their chlorides

Answer.
(a) The vertical columns in the periodic table are called ‘groups’. The horizontal rows in the periodic table are called ‘periods’.
(b)

1.  ‘M’ and ‘N’ belong to same
   period but group I and II. Therefore, ‘N’ will be smaller than ‘M’ as atomic size goes on decreasing from left to right.
2.  ‘M’ is more metallic than ‘N’. Metallic character goes on decreasing from left to right as tendency to lose electrons decreases due to decrease in atomic size.
3.  Their valencies are 1 and 2 respectively in forming oxides.
   Valency goes on increasing first
   and then decreases.
4.  MCI, NCI2 are molecular formulae of their chlorides.

LONG ANSWER TYPE QUESTIONS [5 Marks] – Year 2009

Question.14 (a) Which two criteria did Mendeleev use to classify the elements in his Periodic Table?
(b) State Mendeleev’s periodic law.
(c) Why could no fixed position be given to hydrogen in Mendeleev’s Periodic Table?
(i) Sizes of their atoms
(ii) Their metallic characters
(iii) Their valencies in forming oxides
(iv) Molecular formulae of their chlorides
(a) The vertical columns in the periodic table are called ‘groups’. The horizontal rows in the periodic table are called ‘periods’.
(b) (i) ‘M’ and ‘N’ belong to same
period but group I and II. Therefore, ‘N’ will be smaller than ‘M’ as atomic size goes on decreasing from left to right.
(ii) ‘M’ is more metallic than ‘N’. Metallic character goes on decreasing from left to right as tendency to lose electrons decreases due to decrease in atomic size.
(iii) Their valencies are 1 and 2 respectively in forming oxides. Valency goes on increasing first
and then decreases.
(iv) MCI, NCI2 are molecular formulae of their chlorides.
(d) How and why does the atomic size vary as you go
(i) from left to right along a period?
(ii) down a group?
Answer.
(a) (i) Increasing order of atomic mass as physical property and similarities in chemical properties of elements.
(ii) The formulae and nature of hydrides and oxides formed by elements was treated as basic chemical property for its classification.
(b) Properties of elements are the periodic functions of their atomic masses.
(c) It is because it resembles both alkali metals as well as halogens.
(d) (i) Atomic size goes on decreasing
from left to right because one proton and one electron is being added successively therefore, force of attraction between . valence electrons and nucleus increases hence, the atomic size decreases.
(ii) The atomic size goes on increasing from top to bottom in a group because number of shells keep on increasing therefore, distance between nucleus and valence electrons increases.

Question.15 (a) did Mendeleev have gaps in his periodic table?
(b) any three limitations of Mendeleev’s classification.
(c) does electronic configurations of atoms change in a period with increase in atomic number?
Answer.(a)Gaps were left for undiscovered elements in the Mendeleev’s Periodic Table.
(b)(i) Position of hydrogen was not justified.
(ii)Increasing order of atomic mass could not be maintained.
(iii) Isotopes have similar chemical properties but different atomic masses, they cannot be given separate places.
(c)Number of shells remains the same, number of valence electrons goes on increasing
from left to right in a period till octet is comilete,e.g.

SHORT ANSWER TYPE QUESTIONS[II] [3 Marks] – Year 2010

Question.16 Atoms of seven elements A, B, C, D, E, F and G have a different number of electronic shells but have the same number of electrons in their outermost shells. The elements A and C combine with chlorine to form an acid and common salt respectively. The oxide of element A is liquid at room temperature and is a neutral substance, while the oxides of the remaining six elements are basic in nature. Based on the above information, answer the following   questions:  What could the element A be?
(i) Will elements A to G belong to the same period or same group of the periodic table?
(iii) Write the formula of the compound formed by the reaction of the element A with oxygen,
(iv)Show the formation of the compound by a combination of element C with chlorine with the help of electronic structure.
(v) What would be the ratio of number of combining atoms in a compound formed by the combination of element A with carbon?
(vi)Which one of the given elements is likely to have the smallest atomic radius?
Answer.
(i)’A’ is hydrogen because its oxide H₂O is liquid at room temperature .
(ii)A to G belong to same group of the periodic table as these have same number of valence electrons.

Question.17 In the following table, six elements A, B, C, D, E and F (here letters are not the usual symbols of the elements) of the Modern Periodic Table with atomic numbers 3 to 18 are given:

(a) Which of these halogen ?is (i) a noble gas, (ii) a halogen
(b) If B combines with F, what would be the formula of the compound formed?
(c)Write the electronic configurations of C and E.
Answer.

Question.18 In the following table, are given eight elements A, B, C, D, E, F, G and H (here letters are not the usual symbols of the elements) of the Modern Periodic Table with the atomic numbers of the elements in parenthesis.

1.  What is the electronic configuration of F?
2. What is the number of valence electrons in the atom of F?
3. What is the number of shells in the atom of F?
4.  Write the size of the atoms of E, F, G and H in decreasing order,
5.  State whether F is a metal or a non-metal.
6. Out of the three elements B, E and F, which one has the biggest atomic size?

Answer.

1.  F has electronic configuration 2, 8, 2.
2.  F has 2 valence electrons.
3. There are three shells in ‘F’.
4.  H > G > F > E is decreasing order of size of atbms.
5.  ‘F’ is a metal.
6. ‘B’ is having biggest atomic size among B, E and F.

LONG ANSWER TYPE QUESTIONS [5 Marks] – Year 2010

Question.19 Atoms of eight elements A, B, C, D, E, F, G and H have the same number of electronic shells but different number of electrons in their outermost shell. It was found that elements A and G combine to form an ionic compound. This compound is added in a small amount to almost all vegetable dishes during cooking. Oxides of elements A and B are basic in nature while those of E and F are acidic. The oxide of D is almost neutral. Based on the above information answer the following questions:

1.  To which group or period of the Periodic Table do the listed elements belong?
2.  What would be the nature of compound formed by a combination of elements B and F?
3.  Which two of these elements could definitely be metals?
4.  Which one of the eight elements is most likely to be found in gaseous state at room temperature?
5.  If the number of electrons in the outermost shell of elements C and G be 3 and 7 respectively, write the formula of the compound formed by the combination of C and G.

Answer.

1. A and B belong to group 1 and 2 because they form basic oxides. C belongs to group 13 as it has 3 valence electrons. D belongs to group 14 as it forms almost neutral oxide. E and F belong to group 15 and 16 as they form acidic oxides, G belongs to group 17 as it has 7 valence electrons and H belongs to group 18. They belong to 3rd period of the Periodic Table because AG is NaCI, added in a small amount to almost all vegetable dishes during cooking and Na and Cl belong to 3rd period.
2. Ionic compounds will be formed because ‘B’ is metal and ‘F’ is non-metal. ‘B’ can lose two electrons and ‘F’ can gain two electrons.
3. A and B are definitely metals as they form basic oxides.
4. G and H are gaseous at room temperature.
5.  CG3 is the formula of the compound formed by combination of C and G.

Question.20 Atoms of eight elements A, B, C, D, E, F, G and H have the same number of electronic shells but different number of electrons in their outermost shells. It was found that elements A and G combine to form an ionic compound which can also be extracted from sea water. Oxides of the elements A and B are basic in nature while those of E and F are acidic. The oxide of element D is almost neutral. Answer the following questions based on the information given herein:

1.  To which group or period of the periodic table do the listed elements belong?
2.  Which one of the eight elements is likely to be a noble gas?
3.  Which one of the eight elements would have the largest atomic radius?
4. Which two elements amongst these are likely to be non¬metals?
5.  Which one of these eight elements is likely to be a semi-metal or metalloid?

Answer.

1.  A and B belong to group 1 and 2 because they form basic oxides. C belongs to group 13 as it has 3 valence electrons. D belongs to group 14 as it forms almost neutral oxide. E and F belong to group 15 – and 16 as they form acidic oxides, G belongs to group 17 as it has 7 valence electrons and H belongs to group 18. They belong to 3rd period of Periodic Table because sodium belongs to 3rd period and AG is NaCI, ionic compound of sodium which can be obtained from sea water and A(Na) and G(CI) belong to 3rd period.
2.  H belongs to noble gas.
3. A has the largest atomic radius.
4. E and F are likely to be non¬metals.
5. D is likely to be metalloid or semi-metal.

SHORT ANSWER TYPE QUESTIONS[I] [2 Marks] – Year 2010

Question.21 How can the valency of an element  be determined if its electronic
configuration is known? What will be ‘ the valency of an element of atomic number 9 (nine)?
Answer. If the element has 1, 2, 3, 4 valence electrons, its valency will be 1, 2, 3, 4
respectively. If the element has 5, 6, 7, 8 valence electrons, its valency will be 3, 2, 1, 0. Element with atomic number 9 has electronic configuration 2, 7. So, its valency will be 1.

Question.22 How does the electronic configuration of an atom of an element relate to its position in the modern periodic table? Explain with one example.
Answer. The position of element depends upon number of valence electrons which depend upon electronic configuration. Those elements which have same valence electrons, occupy same group.
Those elements which have one valence electron belong to group 1.
Elements with two valence electrons belong to group 2.
Period number is equal to number of shells.
If valence electrons are equal to 1, it belongs to group 1. If it has 2 shells, it belongs to second period, e.g. if element ‘X’ has atomic number 11, its electronic configuration is 2, 8,1. It has one valence electron, it belongs to group 1 and it has three shells therefore, it is in third period.

Question.23 The atomic numbers of three elements, X, Y and Z are 9,11 and 17 respectively. Which two of these elements will show similar chemical properties? Why?
Answer. Electronic configuration of X, Y and Z will be:
X(9) : 2, 7
Y(11) : 2, 8, 1
Z(17) : 2, 8, 7
X and Z will show similar chemical properties due to same number of valence electrons.

Question.24 On the basis of electronic configuration, how will you identify the first and the last element of a period?
Answer. First element has 1 valence electron and last element has 8 valence electrons. Number of shells remain the same in the same period.

Question.25 In the modern periodic table, the element Calcium (atomic number = 20) is surrounded by elements with atomic numbers 12, 19, 21 and 38. Which of these elements has physical and chemical properties resembling those of Calcium and why?
Answer. Elements with atomic number 12, 38 resemble calcium in physical and chemical properties because they have same number of valence electrons and belong to same group 2.
Mg(12) : 2, 8, 2
Ca(20) : 2, 8, 8, 2
Sr(38) : 2, 8, 18, 8, 2

Question.26. How does the metallic character of elements change along a period of the periodic table from the left to the right and why?
Answer. The metallic character goes on decreasing along a period from left to right because atomic size goes on decreasing therefore, tendency to lose electrons decreases.

Question.27 How does the valency of elements vary
(a) in going down a group, and
(b) in going from left to right in a period of the periodic table?
Answer. (a) Valency remains the same in a group.
(b) Valency first goes on increasing from left to right in a period till middle of period, then decreases.

Question.28 In the periodic table, how does the tendency of atoms to lose electrons change on going from

1. left to right across a period?
2.  top to bottom in a group?

Answer.

1. Tendency to lose electrons decreases from left to right across a period.
2. Tendency to lose electrons increases from top to bottom in a group.

Question.29 Give reasons:

1. Elements in a group have similar chemical properties.
2. Elements of Group I form ions with a charge of +1.

Answer.

1. Elements in a group have same number of valence electrons and same valency therefore have similar chemical properties.
2.  It is because elements of group 1 lose one electron to acquire +1 charge and become stable.

SHORT ANSWER TYPE QUESTIONS[II] [3 Marks] – Year 2010

Question.30 Two elements X and Y belong to group 1 and 2 respectively in the same period of periodic table. Compare them with respect to:
periodic table from the left to the right and why?

1.  the number of valence electrons in their atoms
2. their valencies
3. metallic character
4. the sizes of their ato
5. formulae of their oxides
6. formulae of their chlorides

Answer.

1. ‘X’ has 1 valence electron, Y has 2 valence electrons.
2. ‘X’ has valency equal to 1, V has valency equal to 2.
3. ‘X’ is more metallic than Y.
4. ‘X’ is bigger than Y.
5. X20 and YO are formulae of their oxides.
6. and YCI2 are formulae of their chlorides.

Question.31 The atomic number of an element is 16. Predict

1.  the number of valence electrons in its atom
2. its valency
3. its group number
4. whether it is a metal or a non- metal
5.  the nature of oxide formed by it
6. the formula of its chloride

Answer. The electronic configuration of S(16) is 2, 8, 6.

1.  6
2. 2
3. 16
4.  Non-metal
5.  Acidic oxide
6. SCl₂is a formula of its chloride.

Question.32 The positions of three elements A,
B and C in the periodic table are
indicated below:
Group 16         Group 17
—                       — (First Period)
—                       A (Second Period)
—                       — (Third Period)
B                        C (Fourth Period)
(a) State whether element C would be a metal or a non-metal. Why?
(b) Which is the more active element, A or C? Why?
(c) Which type of ion (cation or anion)
will be formed by the element C? Why?
Answer.
(a) ‘C will be non-metal because it has 7 valence electrons, it can gain one electron easily.
(b) ‘A’ is more active element than ‘C’ because ‘A’ can gain electron easily.
(c) ‘C’ will gain electron to become negative ion, ie. anion because it will have electrons more than protons.

SHORT ANSWER TYPE QUESTIONS[I] [2 Marks] – Year 2012

Question.33 An element ‘X’ has atomic number 13.
(a) Write its electronic configuration.
(b) State the group to which ‘X’ belongs.
(c) Is ‘X’ a metal or a non-metal?
(d) Write the formula of its bromide.
Answer.

Question.34 State the Modern Periodic Law for classification of elements. How many
(a) groups and (b) periods are there in the Modern Periodic Table?
Answer. ‘Properties of elements are the periodic
function of their atomic number.’
(a) There are 18 groups and
(b) 7 periods in the Modern Periodic Table.

Question.35 An element ‘M’ has atomic number 11.
(a) Write its electronic configuration.
(b) State the group to which ‘M’ belongs.
(c) Is ‘M’ a metal or a non-metal?
(d) Write the formula of its chloride.
Answer.

Question.36 the formula of its oxide An element ‘M’ has atomic number 12.
(a) Write its electronic configuration.
(b) State the group to which ‘M’ belongs.
(c) Is ‘M’ a metal or a non-metal?
(d) Write.
Answer.

Question.37 Choose from the following:
6^C, 8^O, 10^Ne, 11^Na,14^Si
(a) Elements that should be in the same period.
(b) Elements that should be in the same group.
State reason for your selection in each case.
Answer.
(a) 6^C, 8^O, 10^Ne are in same period, Le.
2nd period as they have two shells. nNa and 14Si are in same period, i.e. 3rd period as they have three shells.
(b)6^C,14^Si are in same group because they have same number of valence electrons, i.e. four.

Question.38 An element ‘X’ belongs to 3rd period and group 17 of the periodic table. State its (a) electronic configuration, (b) valency. Justify your answer with reasoning.
Answer.
(a) X(17) : 2, 8, 7
(b) Valency : 1
It has atomic number 17 and therefore, electronic configuration will be 2, 8, 7. It can gain one electron to become stable therefore, its valency is equal to 1. It belongs to third period, as it has three shells. It belongs to group 17 because it has 7 valence electrons.

Question.39 The formula of magnesium oxide is MgO. State the formula of barium nitrate and barium sulphate, if barium belongs to the same group as magnesium.
Answer.

Question.40 Choose from the following:
20^Ca,3^Li,11^Na,10^Ne
(a) An element having two shells completely filled with electrons.
(b) Two elements belonging to the same group of the periodic table.
Answer.
(a) 10^Ne has electronic configuration 2, 8. Its both shells are completely filled.
(b) 3^Liand nNa belong to same group of periodic table, ie. 1st group.

Question.41 Why do all the elements of the (a) same group have similar properties, (b) same period have different properties?
Answer.
(a) Elements of same group have similar properties due to same number of valence electrons, therefore, they have same valency.
(b) Elements of same period have different properties as they differ in number of valence electrons.

Question.42 An element ‘E’ has following electronic configuration:

(a) To which group of the periodic table does element ‘E’ belong?
(b) To which period of the periodic table does element ‘E’ belong?
(c) State the number of valence electrons present in element ‘E’.
(d) State the valency of the element ‘E’.
Answer.
(a) ‘E’ belongs to group 16.
(b) It belongs to 3rd period.
(c) It has 6 valence electrons.
(d) Its valency is equal to 2.

Question.43 Choose from the following:
4^Be,9^F,19^K,20^Ca
(a) The element having one electron in the outermost shell.
(b) Two elements of the same group.
Answer.
(a) 19^K has one valence electron.
(b) 4^Beand 20^Cabelong to the same group.

Question.44 An element has atomic number 13.
(a) What is the group and period number to which this element belongs?
(b) Is this element a metal or a non- metal? Justify your answer.
Answer.
(a) It belongs to group 13 and 3rd period.
(b) It is a metal because it can lose 3 electrons to become stable.

Question.45 The electronic configuration of two elements ‘A’ and ‘B’ are 2, 8, 3 and 2, 8, 7 respectively. Find the atomic number of these elements. State the nature and formula of the compound formed by the union of these two elements.
Answer.

Question.46 The atomic number of three elements are given below:

Write the symbol of the element which belongs to (o) group 13, (b) group 15, of the periodic table. State the period of the periodic table to which these elements belong. Give reason for your answer.
Answer.
(a) A belongs to group 13 because its electronic configuration is 2, 3, ie. it has 3 valence electrons.
(b) ‘B’ belongs to group 15 because its electronic configuration is 2, 5, ie. it has 5 valence electrons.
They belong to 2nd period as they ‘ both have two shells.

Question.47 Write the atomic number of these elements. What will be formula of the compound formed and the nature of bond between them when these two elements chemically combine together? 
Answer.
‘A’ has atomic number 17. Its electronic configuration is 2, 8, 7. Its valency is equal to 1. number 20. Its electronic configuration is 2, 8, 8, 2. Its
‘B’ has atomic valency is 2.

Ionic bond will be formed.

Question.48 The atomic numbers of three elements are given below:

Write the symbol of the element which belongs to (a) group 1, (b) group 14, of the periodic table. State the period of the periodic table to which these elements belong. State reason to support your answer. 
Answer.
(a) A belongs to group 1.
(b) B belongs to group 14.
These elements belong to second period because these elements have two shells. A has electronic configuration 2, 1 and has one valence electron so, belongs to group 1. ‘B’ has electronic configuration 2, 4 and has four valence electrons so, belongs to group 14 and period 2. ‘C’ has electronic configuration 2, 7 and has one valence electron. All of them contain two shells and so belong to second period.

SHORT ANSWER TYPE QUESTION[3 Marks]

Question.49 F, Cl and Br are the elements each having seven valence electrons. Which of these (a) has the largest atomic radius, (b) is most reactive? Justify your answer stating reason for each.
Answer.
(a) Bromine has largest atomic radius because it has four shells: 2, 8, 18, 7.
(b) Fluorine is most reactive because it is smallest in size and can gain electron easily.

Question.50 Na, Mg and Al are the elements having one, two and three valence electrons respectively. Which of these elements (a) has the largest atomic radius, (b) is least reactive? Justify your answer stating reason for each. 
Answer. (a) Na has the largest atomic radius because it has 11 protons and 11
electrons, therefore least effective nuclear charge.
(b) Al is least reactive because it has smallest atomic size due to 13 protons and 13 electrons, it has greater effective nuclear charge, therefore, cannot lose electrons easily, hence it is least reactive.

Question.51 (a) How are the following related?

1. Number of valence electrons of different elements in the same group.
2.  Number of shells of elements in the same period.

(b) How do the following change?

1.  Number of shells of elements as we go down a group.
2.  Number of valence electrons of elements on moving from , left to right in a period.
3.  Atomic radius in moving from left to right along a period.
4.  Atomic size down a group.

Answer.
(a)

1. Different elements in same group
   have same number of valence electrons.
2.  Number of shells of elements in same period are equal.

(b)

1. Number of shells of elements
   goes on increasing down the group.
2.  Number of valence electrons of elements goes on increasing on moving from left to right in a period, e.g. lithium has 1, beryllium has 2, boron has 3, carbon has 4, nitrogen has 5, oxygen has 6, fluorine has 7 and neon has 8 valence electrons.
3. Atomic radius goes on decreasing in moving from left to right along a period.
4.  Atomic size goes on increasing down a group.

Question.52.(a) How many periods are there in the Modern Periodic Table of elements?
(b) How do atomic radius, valency and metallic character vary down a group?
(c) How do the atomic size and
metallic character of elements vary as we move from left to right in a period?
Answer.
(a) There are 7 periods.
(b) Atomic radius goes on increasing down the group, valency remains same. Metallic character increases down the group.
(c) Atomic size decreases along a period from left to right. Metallic character decreases along a period from left to right.

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Light  Reflection and Refraction Chapter Wise Important Questions Class 10 Science

SHORT ANSWER TYPE QUESTIONS [II] [3 Marks] – Year 2007

1. A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so that it forms an image at 15 cm from the lens? Also calculate the size of the image formed. [Delhi]
Answer.

2. An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens. [All India]
Answer.

LONG ANSWER TYPE QUESTION [5 Marks] – Year 2007

3. Draw the ray diagram in each case to show the position and nature of the image formed when the object is placed:
(i) at the centre of curvature of a concave mirror
(ii) between the pole P and focus F of a concave mirror
(iii) in front of a convex mirror
(iv) at 2F of a convex lens
(v) in front of a concave lens
Answer.

Nature of image: Real, inverted and same size image is formed at the centre of curvature.

Nature of image: Virtual, enlarged and erect image is formed behind the mirror.

Nature of image: Virtual, erect and diminished, image is formed behind the mirror.

Nature of image: Real, inverted and size to size, image is formed at 2F on the other side of lens.

Nature of image: Virtual, erect and diminished image is formed between O and F on the same side of object.

VERY SHORT ANSWER TYPE QUESTIONS [1 Mark] – Year 2008

4. If a light ray IM is incident on the surface AB as shown, identify the correct emergent ray. [Delhi (C)]

Answer. Ray NQ, as it has to be parallel to ray OS.

5. The refractive indices of four media A, B, C and D are given in the following table:

If light, travels from one medium to another, in which case the change in speed will be (i) minimum, (ii) maximum? [Delhi(C)]
Answer. (i) Minimum change is seen as light moves between 1.50 and 1.52, i.e. B and C.
(ii) Maximum change when light moves between 1.33 and 2.40, i.e. A and D.

6. “The refractive index of diamond is 2.42”. What is the meaning of this statement in relation to speed of light? [Delhi]
Answer.

7. Redraw the given diagram and show the path of the refracted ray: [All India(C)]

Answer.

8. Redraw the given diagram and show the path of the refracted ray: [All India(C)]

Answer.

9. Draw the following diagram in your answer book and show the formation of image of the object AB with the help of suitable rays. [All India]

Answer.

10. Which kind of mirrors are used in the headlights of a motor-car and why? [Foreign]
Answer. Concave mirror, to get the parallel beam of light.

SHORT ANSWER TYPE QUESTIONS [I] [2 Marks] – Year 2008

11. Explain with the help of a diagram, why a pencil partly immersed in water appears to be bent at the water surface. [Delhi]
Answer. Light from different points on the pencil, immersed in water refracts and appears to come from a point above the original position.

12. Draw ray diagrams to represent the nature, position and relative size of the image formed by a convex lens for the object placed:
(a) at 2F₁
(b) between F₁ and the optical centre O of lens: [All India]
Answer.

13. A ray of light, incident obliquely on a face of a rectangular glass slab placed in air, emerges from the opposite face parallel to the incident ray. State two factors on which the lateral displacement of the emergent ray depends. [Foreign]
Answer. Lateral displacement depends on the:

1. angle of incidence,
2. thickness of slab, and
3. refractive index of the material. (any two)

SHORT ANSWER TYPE QUESTIONS [II] [3 Marks] – Year 2008

14. An object 2 cm in size is placed 30 cm in front of a concave mirror of focal length 15 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image? What will be the nature and the size of the image formed? Draw a ray diagram to show the formation of the image in this case. [Delhi(C)]
Answer.

15. An object 2 cm high is placed at a distance of 64 cm from a white screen. On placing a convex lens at a distance of 32 cm from the object it is found that a distinct image of the object is formed on the screen. What is the focal length of the convex lens and size of the image formed on the screen? Draw a ray diagram to show the formation of the image in this position of the object with respect to the lens. [Delhi(C)]
Answer. Since, object-screen distance is double of object-lens separation, the object is at a distance of 2f from the lens and the image should be of the same size of the object.

16. A convex lens has a focal length of 10 cm. At what distance from the lens should the object be placed so that it forms a real and inverted image 20 cm away from the lens? What would be the size of the image formed if the object is 2 cm high? With the help of a ray diagram show the formation of the image by the lens in this case. [All India (C)]
Answer.

LONG ANSWER TYPE QUESTION [5 Marks] – Year 2008

17. (a) It is desired to obtain an erect image of an object, using a concave mirror of focal length 20 cm.
(i) What should be the range of distance of the object from the mirror?
(ii) Will the image be bigger or smaller than the object?
(iii) Draw a ray diagram to show the image formation in this case.
(b) One half a convex lens of focal length 20 cm is covered with a black paper.
(i)Will the lens produce a complete image of the object?
(ii)Show the formation of image of an object placed at 2F1 of such covered lens with the help of a ray diagram.
(iii)How will the intensity of the image formed by half-covered lens compare with non-covered lens? ‘ [Foreign]
Answer.

VERY SHORT ANSWER TYPE QUESTIONS [1 Mark] – Year 2009

18. Redraw the diagram given below in your answer book and show the direction of the light ray after reflection from the mirror. [Delhi (C)]

Answer.

19. Redraw the diagram given below in your answer book and show the direction of the light ray after reflection from the mirror. [Delhi (C)]

Answer.

20. Redraw the diagram given below in your answer book and show the direction of the light ray after reflection from the mirror. [Delhi (C)]

Answer.

21. Redraw the diagram given below in your answer book and show the direction of the light ray after refraction from the lens. [Delhi, All India(C)]

Answer.

22. Why does a ray of light bend when it travels from one medium into another? [Delhi]
Answer. Due to change in velocity in the medium and to reduce the time taken to travel the same.

23. Redraw the diagram given below in your answer book and show the direction of the light ray after refraction from the lens. [All India (C)]

Answer.

SHORT ANSWER TYPE QUESTIONS [I] [2 Marks] – Year 2009

24. What is the minimum number of rays required for locating the image formed by a concave mirror for an object. Draw a ray diagram to show the formation of a virtual image by a concave mirror. [Delhi]
Answer.

25. The refractive index of water is 1.33 and the speed of light in air is 3 x 108 ms-1. Calculate the speed of light in water. [Foreign]
Answer.

26. The refractive index of glass is 1.50 and the speed of light in air is 3 x 108 ms-1. Calculate the speed of light in glass. [Foreign]
Answer.

SHORT ANSWER TYPE QUESTIONS [II] [3 Marks] – Year 2009

27. For which position of the object does a convex lens form a virtual and erect image? Explain with the help of a ray diagram. [All India]
Answer. When the object is placed between the focus and the optical centre, a virtual and erect image is formed.

VERY SHORT ANSWER TYPE QUESTIONS [1 Mark] – Year 2010

28. Explain why a ray of light passing through the centre of curvature of a concave mirror, gets reflected along the same path. [Delhi]
Answer. The ray passing through the centre of curvature incident to the mirror along its normal so ∠i= ∠r = 0. Therefore, the ray retraces its path.

29. What is the nature of the image formed by a concave mirror if the magnification produced by the mirror is +3? [Delhi]
Answer. Positive sign of magnification indicates that image is virtual, erect and enlarged.

30. Between which two points of a concave mirror should an object be placed to obtain a magnification of -3? [Delhi]
Answer. Negative sign of magnification indicates that image is real and inverted. Also size of image is enlarged. So, object must be positioned between F and 2F, i.e. C.

31. “The refractive index of carbon disulphide is 1.63.” What is the meaning of this statement in relation to speed of light? [Delhi]
Answer. Speed of light in carbon disulphide is 1/1.63 times the speed of light in free space.

32. The outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a mirror. What will be the focal length of this mirror? Which type of spherical mirror will it provide? [Delhi]
Answer. f = R/2 = 25 cm. It will form a convex mirror.

33. Between which two points related to a concave mirror should an object be placed to obtain on a screen an image twice the size of the object? [All India]
Answer. Real Image: Between F and C.

34. How should a ray of light be incident on a rectangular glass slab so that it comes out from the opposite side of the slab without being displaced? [Foreign]
Answer. Along the normal to the surface or at an incident angle of i = 0°.

35. A girl was playing with a thin beam of light from her laser torch by directing it from different directions on a convex lens held vertically. She was surprised to see that in a particular direction the beam of light continues to move along the same direction after passing through the lens. State the reason for this observation. [Foreign]
Answer. A ray of light passing through the optical centre of the convex lens will continue to move along the same direction after refracting through the lens.

36. A ray of light enters a rectangular glass slab of refractive index 1.5. It is found that the ray emerges from the opposite face of the slab without being displaced. If its speed in air is 3 x 108 ms-1 then what is its speed in glass? [Foreign]
Answer.

37. The speed of light in a transparent medium is 0.6 times that of its speed in vacuum. What is the refractive index of the medium? [Foreign]
Answer.

SHORT ANSWER TYPE QUESTION [I] [2 Marks] – Year 2010

38. In an experiment with a rectangular glass slab, a student observed that a ray of light incident at an angle of 55° with the normal on one face of the slab, after refraction strikes the opposite face of the slab before emerging out into air making an angle of 40° with the normal. Draw a labelled diagram to show the path of this ray. What value would you assign to the angle of refraction and angle of emergence? [All India]
Answer.

SHORT ANSWER TYPE QUESTION [II] [3 Marks] – Year 2010

39. At what distance should an object be placed from a convex lens of focal length 18 cm to obtain an image at 24 cm from it on the other side. What will be the magnification produced in this case? [Delhi]
Answer.

40. How far should an object be placed from a .convex lens of focal length 20 cm to obtain its image at a distance of 30 cm from the lens? What will be the height of the image if the object is 6 cm tall? [All India]
Answer.

41. The image of an object placed at 60 cm in front of a lens is obtained on a screen at a distance of 120 cm from it. Find the focal length of the lens. What would be the height of the image if the object is 5 cm high? [Foreign]
Answer.

SHORT ANSWER TYPE QUESTION [I] [2 Marks] – Year 2011

42. State the two laws of reflection of light. [Delhi]
Answer. Laws of reflection of light are:

1. The angle of incidence is equal to the angle of reflection.
2. The incident ray, the normal to the reflecting surface at the point of incidence and reflected ray from that point, all lies in the same plane.

43. Define and show on a diagram, the following terms relating to a concave mirror:
(i) Aperture
(ii) Radius of curvature [Foreign]
Answer. (i) The diameter of the reflecting surface of the mirror is called aperture.

(ii) The radius of the sphere of which the reflecting surface of the spherical mirror forms a part is called the radius of curvature of the mirror.

44. Define the focus of a concave mirror. If the radius of curvature of a convex mirror is 30 cm, what would be its focal length? [Foreign]
Answer. The point on the principal axis where all the rays parallel to it meet after reflection is called focus. Since, R = 30 cm and f=R/2 we have, f=+15 cm for a convex mirror.

45. Distinguish between a real and a virtual image of an object. What type of image is formed (i) by a plane mirror, (ii) on a cinema screen? [Foreign]
Answer. If light rays after reflection converge to a point to form an image on its own, it is called a real image. If they are diverging, then they form a virtual image. Real image can be obtained on a screen, while a virtual image cannot be.
(i) Plane mirror forms virtual image.
(ii) On cinema screen, real image is formed.

SHORT ANSWER TYPE QUEST10NS [II] [3 Marks] – Year 2011

46. Draw a ray diagram and also state the position, the relative size and the nature of image formed by a concave mirror when the object is placed at the centre of curvature of the mirror. [Delhi]
Answer.

47. Define ‘refractive index of a transparent medium.’ What is its unit? Which has a higher refractive index, glass or water? [Delhi]
Answer. The ratio of the speed of light in the free space (c) to the speed of light in given medium (ѵ) is called its refractive index.
n=c/ѵ
It has no unit. Glass has more refractive index than water.

48. A ray of light travelling in air enters obliquely into water. Does the light ray bend towards or away from the normal ? Why? Draw a ray diagram to show the refraction of light in this situation. [Delhi]
Answer. Light bends towards the normal because water is denser than air.

The ray bends towards the normal because it has to travel with a lesser speed in water but with shorter time.

49. (a) “The refractive index of diamond is 2.42”. What is the meaning of this statement?
(b) Name a liquid whose mass density is less than that of water but it is optically denser than water. [Delhi]
Answer. (a) This means that the ratio of speed of light in air and the speed of light in diamond is equal to 2.42.  (b) Kerosene

50. An object is placed between infinity and the pole of a convex mirror. Draw a ray diagram and also state the position, the relative size and the nature of the image formed. [All India]
Answer.

51. What is the principle of reversibility of light? Show that the incident ray of light is parallel to the emergent ray of light when light falls obliquely on a side of a rectangular glass slab. [All India]
Answer. The final path of the ray of light after reflections or refractions is reversed; the ray retraces its entire path. This principle is called reversibility of light.


Hence incident ray PQ is parallel to the emergent ray RS when light falls obliquely on a side of rectangular glass slab.

52. With the help of a ray diagram explain why a convex mirror is preferred for rear view mirrors in motor cars. [Foreign]
Answer. (i) It always forms a virtual, erect and diminished image.
(ii) The field of view increases while using a convex mirror as shown.

53. What is understood by lateral displacement of light? Illustrate it with the help of a diagram. List any two factors on which the lateral displacement of a particular substance depends. [Foreign]
Answer. Lateral displacement is the perpendicular distance between the incident ray produced and the emergent ray. Lateral displacement in the diagram is BL. The lateral displacement depends on the thickness of the slab, the incident and refraction angles.

54. Draw the ray diagram and also state the position, relative size and nature of the image formed by a concave mirror when the object is placed between its centre of curvature, C and focus, F. [Foreign]
Answer.

LONG ANSWER TYPE QUESTIONS [5 Marks] – Year 2011

55. (a) If the image formed by a lens is diminished in size and erect, for all positions of the object, what type of lens is it?
(b) Name the point on the lens through which a ray of light passes undeviated.
(c) An object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. The distance of the object from the lens is 30 cm. Find (i) the position (ii) the magnification and (iii) the nature of the image formed. [Delhi]
Answer. (a) Concave lens.
(b) Optical centre.
(c) u = – 30 cm, f = 20 cm

(iii) Image is real as v > 0, inverted and enlarged.

56. (a) What is meant by ‘power of a lens’?
(b) State and define the S.I. unit of power of a lens.
(c) A convex lens of focal length 25 cm and a concave lens of focal length 10 cm are placed in close contact with each other. Calculate the lens power of this combination. [All India]
Answer.

57. (а) Draw a ray diagram to show the formation of image of an object placed between infinity and the optical centre of a concave lens.
(b) A concave lens of focal length 15 cm forms an image 10 cm from the lens. Calculate
(i) the distance of the object from the lens.
(ii) the magnification for the image formed.
(iii) the nature of the image formed. [All India]
Answer. (a) Image formation when the object is at any position between infinity and optical centre:

58. (a) Under what condition will a glass lens placed in a transparent liquid become invisible?
(b) Describe and illustrate with a diagram, how we should arrange two converging lenses so that a parallel beam of light entering one lens emerges as a parallel beam after passing through the second lens.
(c) An object is placed at a distance of 3 cm from a concave lens of focal length 12 cm. Find the (i) position and (ii) nature of the image formed. [Foreign]
Answer. (a) When the refractive index of glass lens becomes equal to the refractive index of transparent liquid, the glass lens will become invisible.
(b) Parallel beam converges at focus of the first lens and emerges parallel as it is at the focus of second lens.

59. (a) With the help of a ray diagram explain why a concave lens diverges the rays of a parallel beam of light.
(b) A 2.0 cm tall object is placed perpendicular to the principal axis of a concave lens of focal length 15 cm. At what distance from the lens, should the object be placed so that it forms an image 10 cm from the lens? Also find the nature and the size of image formed. [Foreign]
Answer. (a) When a parallel beam of light incident on a front face of concave lens, each ray of light will refract towards the normal to the surface as it moves from rarer to denser medium and travels in a straight line inside the lens until it reaches the ‘ back face of the lens. At the back face boundary, each ray of light will again refract and bend away from the normal to the surface as it moves from denser to rarer medium. The course of ray of light is shown in the following figure.

Thus, because of the concave shape of both the faces, the double concave lens diverge the rays of parallel beam of incident light.

SHORT ANSWER TYPE QUESTION [I] [2 Marks] – Year 2012

60. List four properties of the image formed by a plane mirror. [Delhi]
Answer. Properties of image formed by a plane mirror:

1. It is always virtual and erect.
2. Its size is equal to that of the object.
3. It is formed at the same distance behind the mirror as the object is in front of the mirror.
4. It is laterally inverted.

61. List four properties of the image formed by a convex mirror. [Delhi]
Answer. Properties of image formed by a convex mirror:

1. It is always formed behind the mirror, between the pole and its focus.
2. It is always virtual and erect.
3. Its size is always smaller than the object.
4.  Magnification is always positive.

62. List four properties of the image formed by a concave mirror, when object is placed between focus and pole of the mirror. [Delhi]
Answer.

1. The image is formed behind the mirror.
2. It is enlarged, he. magnified.
3. It is virtual.
4. It is erect.

63. To instruct a ray diagram, we use two light rays which are so chosen that it is easy to know their directions after refraction from the lens. List these two rays and state the path of these rays after refraction. Use these two rays to locate the image of an object placed between ‘F and ‘2F of a convex lens. [Foreign]
Answer. Two rays choose for refraction:
(i) A ray of light parallel to the principal axis.
(ii) A ray of light passing through the optical centre of a lens.
Path of these rays after refraction:
In case of convex lens, the first ray will pass through the principal focus on the other side of the lens.
In case of concave lens, the first ray will
(a) appear to diverge or
(b) appear to come from the principal focus positioned on the same side of the object.
The second ray emerge from the lens without any deviation in the path.

SHORT ANSWER TYPE QUESTION [II] [3 Marks] – Year 2012

64. State the type of mirror preferred as (i) rear view mirror in vehicles, (i0 shaving mirror. Justify your answer giving two reasons in each case.[Delhi] ?
Answer. (i) Convex mirror (ii) Concave mirror
Justification:
(i) Convex mirror is used as a rear view mirror because:
(a) it gives a wider field of view as it is curved outwards and
(b) it produces erect and diminished image of the traffic behind the driver of the vehicle.
(ii) Concave mirror is used as a shaving mirror to see a large size image of the face. When the object lies in between pole and principal focus of a concave mirror, it forms a virtual, erect and enlarged image behind it.

65. The image of a candle flame placed at a distance of 45 cm from a spherical lens is formed on a screen placed at a distance of 90 cm from the lens.
Identify the type of lens and calculate its focal length. If the height of the flame is 2 cm, find the height of its image. [Delhi]
Answer.

So, height of image is 4 cm. Negative sign indicates that it is formed below the principal axis.

66. A 4 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 24 cm. The distance of the object from the lens is 16 cm. Find the position, size and nature of the image formed, using the lens formula. [All India]
Answer.

Position of image: Image is formed at a distance of 48 cm from the optical centre of the lens on the same side of the object. It is indicated by the negative sign.
Size of image: It is three times the size of object, i.e. 12 cm.
Nature of image: Positive sign in the image height indicates that image is virtual and erect.

67. Name the type of mirror used in the following situations:
(i) Headlights of a car (ii) Rear-view mirror of vehicles (iii) Solar furnace Support your answer with reason. [All India][Foreign]
Answer. Type of mirror used in
(i) Headlights of a car: Concave mirror Concave mirror is used because light from the bulb placed at the focus of it gets reflected and produces a powerful parallel beam of light to illuminate the road.
(ii) Rear view mirror of vehicles: Convex mirror
Convex mirror is used because it always produces a virtual, and erect image whose size is smaller than the object. Therefore it enables the driver to see wide field view of the traffic behind the vehicle in a small mirror.
(iii) Solar furnace: Concave mirror
Concave mirror has the property to concentrate the sunlight coming from sun along with heat radiation at its focus. As a result, temperature at its focus increases and the substance placed at the focal point gets heated to a high temperature.

68. A 6 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 15 cm. The distance of the object from the lens is 10 cm. Find the position, size and nature of the image formed, using the lens formula. [Foreign]
Answer. For convex lens
f = +15 cm, u = – 10 cm

LONG ANSWER TYPE QUESTIONS [5 Marks] – Year 2012

69. List the sign conventions for reflection of light by spherical mirrors. Draw a diagram and apply these conventions in the determination of focal length of a spherical mirror which forms a three times magnified real image of an object placed 16 cm in front of it. [Delhi ]
Answer. Sign conventions for reflection of light by spherical mirror are:

1.  The object is always placed to the left of the mirror.
2. All the distances parallel to the principal axis are always measured from the pole of the spherical mirror.
3.  All the distances measured along the direction of incident light (along +ve x-axis), are considered to be positive.
4. Those distances measured opposite to the direction of incidence light (i.e. along -ve x-axis), are taken as negative.
5. The distances measured in upward direction, i.e. perpendicular to and above the principal axis (along +ve y-axis), are taken as positive.
6. The distances measured in the downward direction, (along -ve y-axis), i.e. perpendicular to and below the principal axis are taken as negative.
   

So, focal length of spherical mirror is 12 cm. Negative sign of focal length indicates that mirror is concave in nature.

70. State the law of refraction of light that defines the refractive index of a medium with respect to the other. Express it mathematically. How is refractive index of any medium ‘A’ with respect to a medium ‘B’ related to the speed of propagation of light in two media A and B? State the name of this constant when one medium is vacuum or air.
The refractive indices of glass and water with respect to vacuum are 3/2 and 4/3 respectively. If the speed of light in glass is 2 x 108 m/s, find the speed of light in (i) vacuum, (ii) water. [Delhi]
Answer. Snell’s law: The ratio of sine of angle of incidence (i.e. sin i) to the sine of angle of refraction (i.e. sin r) is always constant for the light of given colour and for the given pair of media.

71. To construct a ray diagram, we use two light rays which are so chosen that it is easy to know their directions after reflection from the mirror. List these two rays and state the path of these rays after reflection. Use these rays to locate the image of an object placed between centre of curvature and focus of a concave mirror. [All India]
Answer. Rays which are chosen to construct ray diagram for reflection are:
(i) A ray parallel to the principal axis and
(ii) A ray passing through the centre of curvature of a concave mirror or appear to pass through the centre of curvature of convex mirror.
Path of these rays after reflections is:
(i) After reflection, the first ray will pass through the principal focus of a concave mirror or appear to diverge in case of a convex mirror.
(ii) After reflection, the second ray is reflected back along the same path.

72. List the sign conventions that are followed in case of refraction of light through spherical lenses. Draw a diagram and apply these conventions in determining the nature and focal length of a spherical lens which forms three times magnified real image of an object placed 16 cm from the lens. [Foreign]
Answer. Sign conventions for refraction of light through spherical lens are:

1. The object is always placed to the left of the lens so that incident light moves from left to right.
2. All distances are to be measured from the optical centre of the lens.
3. The distances measured in the direction of incident light (along +ve x-axis) will be taken as positive. while those measured to the left of the origin (along -ve x-axis) will be taken as negative.
4. All measurements of heights above the principal axis (along +ve y-axis) will be considered as positive while below it (along -ve y-axis) will be taken as negative.
   
   

So, focal length of the given spherical lens is 12 cm. The positive sign of focal length shows that the nature of spherical lens is convex.

Important QuestionsNCERT SolutionsSample PapersNCERT Exemplar Solutions

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Chemical Reactions and Equations Chapter Wise Important Questions Class 10 Science 

Important QuestionsNCERT SolutionsSample PapersNCERT Exemplar Solutions

Short Answer Type Questions[l] [2 Marks] -Year 2015

1.“We need to balance a skeltal chemical equation.” Give reason to justify the statement.
Answer. Skeltal chemical equation are unbalanced. We need to balance chemical equation because of law of conservation of mass. It states that ‘matter can neither be created nor be destroyed’. Therefore chemical equation must be balanced in each and every chemical reaction.

2.Giving an example list two information which make a chemical equation more useful (informative).
Answer.
(i) Physical state of reactants must be mentioned, e.g.
2H₂ (g) + O₂ (g)——– > 2H₂0 (l)
(ii) Condition in which reaction takes place are written on the arrow head, e.g.

Consider the following chemical reaction
X + Barium chloride——–> Y + Sodium chloride
(White ppt)
(a) Identify ‘X’ and ‘Y’
(b) The type of reaction
(a) ‘X’ is Na2SO₄ and Y is BaSO₄.
(b) The type of reaction
Na₂SO₄ + BaCl₂—–> BaSO₄ + 2NaCl
(White ppt)
The reaction is precipitation reaction. It is also called double displacement reaction.

4. Name the reducing agent in the following reaction:
3MnO₂ + 4Al———— > 3Mn + 2Al₂O₃
State which is more reactive, Mn or A1 and why?
Answer. ‘Al’ is reducing agent.
‘AT is more reactive than Mn v ‘Al’ displaces Mn from its oxide.

5.(i) Write a balanced chemical equation for process of photosynthesis.
   (ii)When do desert plants take up carbon dioxide and perform photosynthesis?
Answer.

(ii) In desert plants the stomata are open at night. They take CO₂ at night and is stored in the form of acid and is used during day time for photosynthesis.

Short Answer Type Questions[ll] [3 Marks] -Year 2015

6.A Name the type of chemical reaction represented by the following equation:

Answer.
(i) Combination reaction
(ii) Double displacement reaction (Precipitation reaction)
(iii) Decomposition reaction.

7. Write the chemical equation of the reaction in which the following changes have taken place with an example of each: 
(i) Change in colour
(ii) Change in temperature
(iii) Formation of precipitate
Answer.
(i)Cu (s) + 2AgNO₃ (aq)———–> Cu(NO₃)₂(aq) + 2Ag
The solution will become blue in colour and shiny silver metal will be deposited.
(ii) NaOH + HCl ———–> NaCl +  H₂O+ heat
The temperature will increase because heat will be evolved.
(iii) Pb(NO₃)2 (aq) + 2KI (aq)———–> Pbl₂ (s) + 2KNO₃ (aq)
Yellow ppt
Yellow precipitate of Pbl₂will be formed.

8.State the type of chemical reactions and chemical equations that take place in the following:
(i) Magnesium wire is burnt in air.
(ii) Electric current is passed through water.
(iii) Ammonia and hydrogen chloride gases’are mixed.

Answer.

9.(a) Write the essential condition for the following reaction to take place:
2AgBr—-> 2Ag + Br₂
Write one application of this reaction.
(b) Complete the following chemical equation of a chemical reaction 2FeS04 —

(c) What happens when water is added to quick line. Write chemical equation.
Answer.

This reaction is used in photography.

(c) Slaked lime is formed with hissing sound and lot of heat is envolved.

10. 2g of ferrous sulphate crystals are heated in a dry boiling tube.
(i) List any two observations.
(ii) Name the type of chemical reaction taking place.
(iii) ‘Write the chemical equation for the reaction.
Answer.
(i) •Green colour of Fe SO₄ disappears and reddish brown solid is formed.
• Smell of burning sulphur.
(ii) Decomposition reaction

Long Answer Type Questions [5 Marks] -Year 2015

11. (a) Define a balanced chemical equation. Why should an equation be balanced?
(b) Write the balanced chemical equation for the following reaction:
(i) Phosphorus burns in presence of chlorine to form phosphorus penta chloride.
(ii) Burning of natural gas.
(iii) The process of respiration.
Answer.
(a) Balanced chemical equation has an equal number of atoms of different elements in the reactants and products. According to law of conservation of mass, matter can neither be created nor be destroyed in a chemical reaction.
(b)(i) P₄ (s) + 10Cl₂ (g) ———> 4PCl₅ (S)
(i)CH₄ (g) + 2O₂ (g) ———> CO₂ (g) + 2H₂O(l) + heat energy
(iii) C₆H₁₂O₆ (s) + 6O₂ (g) + 6H2O ———> 6CO₂ (aq) + 12H₂O (l) + energy

12.(a) Explain two ways by which food industries prevent rancidity.
(b) Discuss the importance of decomposition reaction in metal industry with three points.
Answer.
(a) (i) Rancidity can be prevented by adding antioxidants to food containing
fat and oil, e.g. butylated hydroxy anisole is added to butter as antioxidant.
(ii) It can be prevented by packaging fat and oil containing foods in nitrogen gas.
(b) (i) Molten NaCl is electrolytically decomposed to form sodium metal.
(ii) Aluminium metal is obtained by electric decomposition of bauxite ore mixed with cryolite.
(iii) Carbonate ores are thermally decomposed to give metal oxide which on reduction give metal.

Short Answer Type Question[I] [2 Marks] -Year 2014

13. What is observed when a solution of potassium iodide solution is added to a solution of lead nitrate? Name the type of reaction. Write a balanced chemical equation to represent the above chemical reaction.
Answer.Yellow precipitate of lead iodide is formed. It is precipitation reaction.
Pb( NO₃)₂ (aq) + 2KI (aq) —-> Pbl₂ (s) + 2KNO₃ (aq)
It is also called double displacement reaction.

short Answer Type Question[ll] [3 Marks] -Year 2014

14.Write chemical equation reactions taking place when carried out with the help of
(a) Iron reacts with steam
(b) Magnesium reacts with dil HCl
(c) Copper is heated in air.
Answer.

Long Answer Type Question [5 Marks] -Year 2014

15.(a) Write one example for each of decomposion reaction carried out with help of
(i) Electricity (ii) Heat (iii) Light
(b) Which of the following statements is correct and why copper can displace silver from silver nitrate and silver can displace copper from copper sulphate solution.
Answer.

Short Answer Type Questions[ll] [3 Marks] -Year 2013

16.Which products will be obtained when lead nitrate is heated simply. Write balanced chemical equation for the reaction? State the type of chemical reaction that occur in the change.
Answer. Lead monoxide, nitrogen dioxide and oxygen gas will be liberated.

It is thermal decomposition reaction.

17. What is meant by skeltal type chemical equation? What does it represent? Using the equation for electrolytic decomposition of water, differentiate between a skeltal chemical equation and a balanced chemical equation.
Answer. The equations in which gaseous are written in atomic form instead of molecular form and equation is not balanced, are called skeltal type equation. They represent gaseous elements formed in atomic state and equation is not balanced

Short Answer Type Questions[l] [2 Marks]-Year 2012

18.Write balanced chemical equations for the following reactions.
(i) Silver bromide on exposure to sunlight decomposes into silver and bromine,
(ii) Sodium metal reacts with water to form sodium hydroxide and hydrogen gas.
Answer.

19.Identify the type of reaction(s) in the following equations.
(i)CH₄ + 2O₂ CO₂ + 2 H₂O
(ii) Pb(NO₃)2 + 2KI ——–>Pbl₂ + 2KNOs
(iii) CaO +  H₂O ——–> Ca(OH)₂
(iv) CuSO₄ + Zn ——–> ZnSO₄ + Cu
Answer.
(i) Combustion reaction and oxidation reaction.
(ii)Double displacement reaction and precipitation reaction.
(iii) Combination reaction.
(iv) Displacement reaction.

20.Write balanced equation for the reaction between magnesium and hydrochloric acid. Name the product obtained, identify the type of reaction.
Answer.

The product formed is magnesium chloride and hydrogen gas.
It is a displacement reaction.

21.Describe an activity to observe what happens when quick lime is added to water taken in a beaker. State two important observations and name the type of reaction taking place.
Answer.
Aim: To observe what happens when quicklime is added to water taken in a beaker.
Materials Required:- Quicklime (calcium oxide), water, beaker.

Procedure:
1. Take 5 g of calcium oxide in a beaker.
2. Add water to it slowly.
3. Touch the beaker.
4. Note down the observations.
Observation: Calcium oxide reacts with water
vigorously to form calcium hydroxide with the evolution of heat.
Chemical Reaction:

Conclusion: The reaction between CaO (Calcium oxide) and H₂O is a combination reaction. It is an exothermic process because heat is evolved.

22.What is the colour of ferrous sulphate crystals? How does this colour change after heating?
Answer.The colour of ferrous sulphate is pale green. The colour changes to reddish brown on heating due to formation of iron (III) oxide.
Give an example each for thermal decomposition and photochemical decomposition reactions. Write relevant balanced chemical equations also.
Thermal decomposition reaction:

Photochemical decomposition reaction:

24. Why does the colour of copper sulphate solution change when an iron nail is dipped in it? Write two observations.
Answer. It is because displacement reaction takes place.
Iron displaces copper from copper sulphate solution and forms pale green
coloured solution of FeS04 and reddish brown copper metal gets deposited.
Fe(s) + CuS0₄(aq) ——–> FeS0₄(aq) + Cu(s)

25. Translate the following statement into chemical equation and then balance it Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate. State the two types in which this reaction can be classified.
Answer. 3BaCl₂(aq) + A1₂(S0₄)₃(aq) ——–> 3BaS0₄(s) + 2AlCl₃(aq)
It can be classified as double displacement as well as precipitation reaction.

26. Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.
Answer. In decomposition reaction, a compound is broken down into simpler compounds or elements, e.g.

Combination reaction is a reaction in which two or more elements or compounds combine to form a new compound, e.g.

Thus, decomposition and combination reactions are opposite to each other.

Short Answer Type Questions[ll] [3 Marks]  -Year 2012

27. The following diagram displays a chemical reaction. Observe carefully and answer the following questions

(a) Identify the type of chemical reaction that will take place and define it. How will the colour of the salt change?
Write the chemical equation of the reaction that takes place.
(c) Mention one commercial use of this salt.
Answer. (a) Photochemical decomposition reaction: Those reactions in which a compound breaks down into simple substances in presence of light are called photochemical decomposition reaction. The colour of salt will change from white to grey.

(c) Silver chloride is used in photography.

28. What is rancidity? Mention any two ways by which rancidity can be prevented.
Answer. The process in which taste and smell of food gets spoiled is called rancidity. It happens due to oxidation.
Prevention from rancidity:
(i) Antioxidants are added to fatty acids to prevent oxidation, e.g. chips are packed in presence of nitrogen gas which prevents spoilage by oxidation.
(ii)Food should be kept in airtight container in refrigerator.

29.Write balanced chemical equation for the reactions that take place during respiration. Identify the type of combination reaction that takes place during this process and justify the name. Give one more example of this type of reaction.
Answer. CgH₁₂0₆ + 6O₂ —————> 6CO₂ + 6H₂0 + heat
It is an exothermic combination reaction because heat is evolved.
CH₄(g) + 2O₂(g) ————–>CO₂ (g) + 2H₂0
Combustion of methane is another example of exothermic combination reaction.

30. What is redox reaction? Identify the substance oxidised and the substance reduced in the following reactions.
(i)2PbO + C —–> 2Pb + CO₂
(ii)MnO₂ + 4HCl —–> MnCl₂ + 2H₂0 + Cl₂
Answer. Those reactions in which oxidation and reduction takes place simultaneously are called redox reactions.
(i) PbO is getting reduced and C is getting oxidised.
(ii) MnOs is getting reduced and HCl is getting oxidised.

31. Write the balanced chemical equations for the following reactions and identify the type of reaction in each case.
Thermite reaction, iron (III) oxide reacts with aluminium and gives molten iron and aluminium oxide.
Answer.

It is a displacement reaction because A1 is displacing Fe from Fe₂O₃.
Molten iron is used’for repairing broken railway tracks.

32. A solution of potassium chloride when mixed with silver nitrate solution, an insoluble white substance is formed. Write the chemical reaction involved and also mention the type of the chemical reaction?
Answer.

.
It is a double displacement reaction. It is also a precipitation reaction as AgCl is a white precipitate.

Very Short Answer Type Questions [1 Mark] -Year 2011

33.State one basic difference between a physical change and a chemical change.
Answer. In physical change, no new substance is formed, whereas in a chemical change, new substance(s) is/are formed.

34 What is meant by a chemical reaction?
Answer. The reaction representing a chemical change is called a chemical reaction.

35.AgN0₃(aq) + NaCl(aq)——————– > AgCl(s)₄↓ + NaN0₃(aq)
FeS + H₂S0₄————- > FeS0₄ + H₂S↑
Consider the above mentioned two chemical equations with two different kinds of arrows (↑and ↓) along with product. What do these two different arrows indicate?
Ans,↑shows the gas is evolved whereas ↓shows insoluble substance (precipitate) is formed.

36. Hydrogen being a highly inflammable gas and oxygen being a supporter of combustion, yet water which is a compound made up of hydrogen and oxygen is used to extinguish fire. Why?
Answer. It is because properties of compound (H₂O) are different from properties of its constituting elements, i.e. H₂and O₂.

Short Answer Type Questions[l] [2 Marks] -Year 2011

37.Using a suitable chemical equation, justify that some chemical reactions are determined by:
(i) change in colour, (ii) change in temperature.
Answer.

38.(a) A solution of substance ‘X’ is used for white washing. What is the substance ‘X’? State the chemical reaction of ‘X’ with water.
(b) Why does the colour of copper sulphate solution change when an iron nail is dipped in it?
Answer.
(a) ‘X’ is calcium oxide (CaO).
CaO(s) + H₂O(l) —–> Ca(OH)₂(aq) + heat
(a) It is because iron displaces copper from CuS0₄ to form FeS0₄ which is pale green.
Fe(s) + CUS0₄ (aq)—–> FeS04(aq) + Cu(s)
Blue                       Pale green

39.Balance the following chemical equations.

Answer.

40.Write the balanced equation for the. following reaction and identify the type of reaction in each case.
(i) Potassium bromide + Barium iodide—-> Potassium iodide + Barium bromide.
(ii) Hydrogen(g) + Chlorine(g)—-> Hydrogen chloride(g)
Answer.

41. A zinc plate was put into a solution of copper sulphate kept in a glass container. It was found that blue colour of the solution gets fader and fader with the passage of time. After few days, when zinc plate was taken out of the solution, a number of holes were observed on it.
(i) State the reason for changes observed on the zinc plate.
(ii) Write the chemical equation for the reaction involved.
Answer.
(i) It is because zinc has displaced copper from CuS04. Zinc metal has been used to form zinc sulphate, therefore, number of holes were observed.

42. A white salt on heating decomposes to give brown fumes and a residue is left behind.
(i) Name the salt.
(ii) Write the equation for the decom-position reaction.
Answer.
(i) Lead nitrate is white salt.

43. When a solution of potassium iodide is added to a solution of lead nitrate in a test tube, a reaction takes place.
(a) What type of reaction is this?
(b) Write a balanced chemical equation to represent the above reaction.
Answer.
(a) Double displacement as well as precipitation reaction.

44. Define combination reaction. Give one example of a combination reaction which is also exothermic.
Answer. A reaction in which two elements or compounds combine to form a single compound is called combination reaction.

It is also an exothermic reaction along with a combination reaction because heat is evolved.
Short Answer Type Questions[ll] [3 Marks]

45.(a) Classify the following reactions into different types.

(b) Which of the above reaction(s) is/are precipitation reaction(s)? Why is a reaction called precipitation reaction?
Answer.
(a) (i) Precipitation reaction (Double displacement reaction)
(ii) Combination reaction (in) Decomposition reaction
(b) Reaction (i) is a precipitation reaction because one of the product formed is insoluble in water.

46. Write balanced equations for the following mentioning the type of reaction involved.
(i) Aluminium + Bromine —–> Aluminium bromide
(ii) Calcium carbonate—–> Calcium oxide + Carbon dioxide
(iii) Silver chloride—–>Silver + Chlorine
Answer.

47.(a) Why is respiration considered as an exothermic reaction?
(b) Define the terms oxidation and reduction.
(c) Identify the substance that is oxidised and reduced in the following reaction.

Answer. (a) It is because heat is evolved during respiration.
(b) Oxidation is a process in which O₂ is added or H₂ is removed or loss of electrons take place. Reduction is a process in which H₂ is added or O₂. is removed or gain of electrons take place.
(c) Zn is getting oxidised, CuO is getting reduced.

48. What is meant by
(i) precipitation reaction,
(ii) exothermic reaction,
(iii) oxidation reaction?
Write balanced chemical equations for an example of each.
Answer.(i) Precipitation reaction: The reaction in which two compounds exchange their
ions and the product formed is insoluble in water is called precipitation reaction.

(ii) Exothermic reaction: The reaction in Which heat is evolved is known as exothermic reaction.

(iii) Oxidation reaction: The reaction in which Og is added or H₂ is removed or loss of electrons takes place is called oxidation reaction.

49.You might have noted that when copper powder is heated in a china dish, the surface of copper powder becomes coated with a black colour substance.
(i) How has this black coloured substance formed?
(ii) What is that black substance?
(iii) Write the chemical equation of the reaction that takes place.
Answer.
(i) Copper reacts with oxygen to form copper oxide which is black, i.e. oxidation of copper takes place.
(ii)Copper oxide

Very Short Answer Type Questions [1 Mark] -Year 2010

50. What happens chemically when quicklime is added to water filled in a bucket?
Answer. Quicklime reacts with water to form slaked lime and produces lot of heat and hissing sound.

51. On what basis is a chemical equation balanced?
Answer. A chemical reaction is balanced on the basis of law of conservation of mass.

52. What change in colour is observed when white silver chloride is left exposed to sunlight? State the type of chemical reaction in this change.
Answer. Silver chloride becomes grey. It is a photochemical decomposition reaction.

53. Write a balanced chemical equation for the reaction between sodium chloride
and silver nitrate indicating the physical state of the reactants and the products.
Answer.

Short Answer Type Questions[l] [2 Marks]

54. What happens when an aqueous solution of sodium sulphate reacts with an aqueous solution of barium chloride? State the physical conditions of reactants in which the reaction between them will not take place. Write the balanced chemical equation for the reaction and name the type of reaction.
Answer. White precipitate of barium sulphate is formed.
If both reactants are in solid state, then the reaction will not take place between them.

It is a double displacement as well as a precipitation reaction.

55. What is a redox reaction? When a magnesium ribbon burns in air with a dazzling flame and forms a white ash, is magnesium oxidised or reduced? Why?
Answer. The reactions in which oxidation (loss of electrons) and reduction (gain of electrons) take place simultaneously are called redox reactions.

Magnesium is getting oxidised because it is losing electrons to form Mg2+ and oxygen is gaining electrons to form O2-, therefore it is getting reduced.

56. Write any two observations in an activity which may suggest that a chemical reaction has taken place. Give an example in support of your answer.
Answer. Any two of these observations will suggest chemical reaction has taken place.
(i) Change in state.
(ii)Change in colour.
(iii) Evolution of gas.
(iv)Change in temperature.
For example, lead nitrate is white crystalline solid which on heating gives yellowish brown solid (lead monoxide). A brown gas and a colourless gas is also evolved. It shows chemical reaction has taken place.

57.When the powder of a common metal is heated in an open china dish, its colour turns black. However, when hydrogen is passed over the hot black substance so formed, it regains its original colour. Based on the above information, answer the following questions.
(i) What type of chemical reaction takes place in each of the two given steps?
(ii) Name the metal initially taken in the powder form. Write balanced chemical equations for both reactions.
Answer.
(i) In first step, oxidation takes place.In second step, redox reaction takes place.
(ii)Metal in the powder form is copper.

Very Short Answer Type Questions [1 Mark] -Year 2009

58.In electrolysis of water, why is the volume of gas collected over one electrode double that of gas collected over the other electrode?
Answer.It is because water contains hydrogen and oxygen in the ratio of 2 : 1.

59.Balance the following chemical equations.
Answer.

Short Answer Type Questions[l] [2 Marks] -Year 2009

60. Name the products formed on strongly heating ferrous sulphate crystals. What type of chemical reaction occurs in this change?
Answer.

It is decomposition reaction.

61. What is an oxidation reaction? Give an example of oxidation reaction. Is oxidation an exothermic or an endothermic reaction?
Answer. The reaction in which oxygen or electronegative element is added or hydrogen or electropositive element is removed or loss of electrons takes place, is called an oxidation reaction, e.g. ,

Oxidation reactions are mostly exothermic in nature because heat is evolved in this process.

62. Describe an activity to demonstrate the change that takes place when white silver chloride is kept in sunlight. State the type of chemical reaction which takes place.
Answer.
Aim: To demonstrate the change that takes place when white silver chloride is kept in sunlight.
Materials Required: AgNO₃(aq), NaCl(aq), test tubes.

Procedure:
1. Take 5 ml of silver nitrate solution in a test tube.
2. Prepare sodium chloride solution in another test tube.
3. Add sodium chloride solution into test tube containing silver nitrate solution.
4. Observe the colour of silver chloride formed chloride to grey silver metal Dry it with the help of filter papers and place it on the watch glass.
5. Place the watch glass under sunlight for sometime.
6. Observe the colour of the silver chloride after sometime. Observation: White silver chloride turns grey in sunlight because silver metal is formed.

Explanation: Silver chloride is photosensitive. It decomposes in presence of sunlight to form silver metal and chlorine gas.
Conclusion: Decomposition of silver chloride in presence of sunlight is photochemical decomposition reaction.

63.When magnesium ribbon burns in air or oxygen, a product is formed. State the type of chemical reaction and name the product formed in the reaction. Write balanced chemical equation of this reaction.
Answer.

The type of reaction is combination reaction and the product formed is magnesium oxide.

64.Distinguish between a displacement reaction and a double displacement reaction. Identify the displacement and the double displacement reaction from the following reactions.
Answer.

Displacement reaction is a reaction in which more reactive metal can displace less reactive metal from its salt solution.
Double displacement reaction are those reactions in which compounds exchange their ions to form two new compounds (?) Double displacement reaction (ii) Displacement reaction

65.When you have mixed the solutions of lead(II) nitrate and potassium iodide,
(i) what was the colour of the precipitate formed and can you name the precipitate?
(ii) write the balanced chemical equation for this reaction.
(iii) is this also a double displacement reaction?
Answer.
(i) The colour of the precipitate is yellow. The name of compound formed as a precipitate is Pbl2 (lead iodide).

(iii) Yes, it is also a double displacement reaction.

66.What do you mean by exothermic and endothermic reactions? Give examples.
Answer.Exothermic reactions are those in which heat is evolved, e.g.

Endothermic reactions are those reactions in which heat is absorbed, e.g.

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Acids  Bases and Salts Chapter Wise Important Questions Class 10 Science

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Short Answer Type Questions[l] [2 Marks] – Year 2015

1.Name the acid present in the following:
(i) Tomato (ii) Vinegar (iii) Tamarind
Answer. (i) Oxalic acid (ii) Acetic acid (iii) Tartaric acid

2.15 mL of water and 10 mL of sulphuric acid are to be mixed in a beaker
(i) State the method that should be followed with reason.
(ii)What is this process called?
Answer.
(i) The acid is to be added slowly in water to prevent the mixture to be splashed. The
reaction is highly exothermic, therefore, constant cooling should be done.
(ii)The process is called dilution.

3. Explain how antacid works.
Answer. Hyperacidity is caused by excess of hydrochloric acid in stomach. Antacid is basic in nature. It neutralizes excess of acid and gives relief from pain caused by hyperacidity.

Short Answer Type Questions[ll] [3 Marks] –Year 2015

4.(a) Define olfactory indicators. Name two subtances which can be used as olfactory indicator.
(b) Choose strong acids from the following:
CH₃COOH, H₂SO₄, H₂CO₃, HNO₃
Answer.
(a) Those substances whose smell (odour) changes in acidic or basic solution are called olfactory indicators, e.g. onion and vanilla.
(b) H₂SO₄ and HNO₃    are strong acids.

5.A white coloured powder is used by doctors for supporting fractured bones.
(a) Write chemical name and formula of the powder.
(b) When this white powder is mixed with water a hard solid mass is obtained. Write balanced chemical equation for the change.
Answer.