NCERT Exemplar Problems Class 11 Mathematics Chapter 11 Conic Sections

Short Answer Type Questions
Q1. Find the equation of the circle which touches the both axes in first quadrant and whose radius is a.
Sol: Given that the circle of radius ‘a’ touches both axis. So, its centre is (a, a).

Q2. Show that the point (x, y) given by   and  lies on a circle .

Q3. If a circle passes through the point (0, 0) (a, 0), (0, b) then find the coordinates of its centre.
Sol: We have circle through the point A(0, 0), B(a, 0) and C(0, b).
Clearly triangle is right angled at vertex A.

So, centre of the circle is the mid point of hypotenuse BC which is (a/2, b/2)

Q4. Find the equation of the circle which touches x-axis and whose centre is (1,2).
Sol: Given that, circle with centre (1,2) touches x-axis.
Radius of the circle is, r = 2
So, the equation of the required circle is:
(x – l)² + (y – 2)² = 2²
=>x²-2x + 1 + y²-4y + 4 = 4
=> x² + y² – 2x-4y + 1 = 0

Q5. If the lines 3x – 4y + 4 = 0 and 6x – 8y – 7 = 0 are tangents to a circle, then find the radius of the circle.
Sol: Given lines are 6x – 8y + 8 = 0 and 6x – 8y – 7 = 0.
These parallel lines are tangent to a circle.

Q6. Find the equation of a circle which touches both the axes and the line 3x – 4y + 8 = 0 and lies in the third quadrant.

Q7. If one end of a diameter of the circle x² + y² -4x -6y + 11 = 0 is (3,4), then find the coordinate of the other end of the diameter.
Sol: Given equation of the circle is:

Q8. Find the equation of the circle having (1, -2) as its centre and passing through 3x +y= 14, 2x + 5y = 18.
Sol: Given lines are 3x + y = 14 and 2x + 5y= 18.

Q9. If the line y= √3 x + k touches the circle x² + y² = 16, then find the value of
Sol: Given line is y = √3 x + k and the circle is x² + y² = 16.

Q10. Find the equation of a circle concentric with the circle x² +y² – 6x + 12y + 15 = 0 and has double of its area.
Sol: Given equation of the circle is:

Q11. If the latus rectum of an ellipse is equal to half of minor axis, then find its eccentricity.

Q12. Given the ellipse with equation 9X² + 25y² = 225, find the eccentricity and foci.

Q13. If the eccentricity of an ellipse is 5/8 and the distance between its foci is 10, then find latus rectum of the ellipse.

Q14. Find the equation of ellipse whose eccentricity is 2/3, latus rectum is 5 and thecentre is (0, 0).

Q15. Find the distance between the directrices of the ellipse 

Q16. Find the coordinates of a point on the parabola y² = 8x whose focal distance is 4.
Sol: Given parabola is y² = 8x

Q17. Find the length of the line-segment joining the vertex of the parabola y² = 4ax and a point on the parabola where the line-segment makes an angle 6 to the x-axis.
Sol: Given equation of the parabola isy² = 4ax.
Let the point on the parabola be P(x₁,,y₁).

Q18. If the points (0, 4) and (0, 2) are respectively the vertex and focus of a parabola, then find the equation of the parabola.

Q19. If the line y = mx + 1 is tangent to the parabola y² = 4x then find the value of m.
Sol: Given that, liney = mx + 1 is tangent to the parabola y² = 4x.

Q20. If the distance between the foci of a hyperbola is 16 and its eccentricity is √2, then obtain the equation of the hyperbola.

Q21. Find the eccentricity of the hyperbola 9y² – 4x² =36
Sol: We have the hyperbola:9y² – 4x² = 36

Q22. Find the equation of the hyperbola with eccentricity 3/2 and foci at (±2, 0).

Long Answer Type Questions

Q23. If the lines 2x – 3y = 5 and 3x-4y = 7 are the diameters of a circle of area 154 square units, then obtain the equation of the circle.
Sol: Given that lines 2x – 3y – 5 = 0 and 3x – 4y -1 = 0 are diameters of the circle. Solving these lines we get point of intersection as (1, -1), which is centre of the circle.

Q24. Find the equation of the circle which passes through the points (2, 3) and (4, 5) and the centre lies on the straight line y – 4x + 3 = 0.
Sol: Let the centre of the circle be C(h, k).
Given that the centre lies on the line y – 4x + 3 = 0.
k — 4h + 3 = 0 or k = 4h — 3
So, the centre is C(h, 4h – 3).

Q25. Find the equation of a circle whose centre is (3, -1) and which cuts off a chord of length 6 units on the line 2x — 5y+ 18 = 0.

Sol: Given centre of the circle 0(3, -1)
Chord of the circle is AB.

Q26. Find the equation of a circle of radius 5 which is touching another circle x² + y² – 2x – 4y – 20 = 0 at (5, 5).

Q27. Find the equation of a circle passing through the point (7, 3) having radius 3 units and whose centre lies on the line y = x -1.
Sol: Given that circle passes through the point A(7, 3) and its radius is 3.

Q28. Find the equation of each of the following parabolas.
(i) Directrix, x = 0, focus at (6, 0)
(ii) Vertex at (0,4), focus at (0, 2)
(iii) Focus at (-1, -2), directrix x – 2y + 3 = 0
Sol: We know that the distance of any point on the parabola from its focus and its directrix is same.
(i) Given that, directrix, x = 0 and focus = (6, 0)
So, for any point P(x, y) on the parabola
Distance of P from directrix = Distance of P from focus =>  x² = (x — 6)² + y²
=>         y²– 12x + 36 = 0
(ii) Given that, vertex = (0,4) and focus = (0, 2)
Now distance between the vertex and directrix is same as the distance between the vertex and focus.
Directrix is y – 6 = 0
For any point of P(x, y) on the parabola
Distance of P from directrix = Distance of P from focus

Q29. Find the equation of the set of all points the sum of whose distances from the points (3, 0) and (9, 0) is 12.

Sol: Let the coordinates of the variable point be (x, y).
Then according to the question,

Q30. Find the equation of the set of all points whose distance from (0,4) are 2/3 of their distance from the line y = 9.
Sol: Let the point be P(x, y).
According to the question

Q31. Show that the set of all points such that the difference of their distances from (4, 0)and (-4, 0) is always equal to 2 represent a hyperbola.

True/False Type Questions

Q33. The line x + 3y = 0 is a diameter of the circle x² + y² + 6x + 2y = 0.
Sol: False
Given equation of the circle is x² + y² + 6x + 2y = 0
Centre = (-3, -1)
Clearly, it does not lie on the line x + 3y = 0 as -3 + 3(-l) = -6.
So, this line is not diameter of the circle.

Q34. The shortest distance from the point (2, -7) to the circle x +y² – 1 4jc – lOy- 151 = 0 is equal to 5.
Sol: False

Q35. If the line lx + my = 1 is a tangent to the circle x² + y² = a², then the point (1, m) lies on a circle.

Q36. The point (1,2) lies inside the circle x² + y² – 2x + 6y + 1 = 0.
Sol: False

Q37. The line lx+ my + n = 0 will touch the parabola^² = 4 ax if In = am².
Sol: True




Fill in the Blanks Type Questions

Q41. The equation of the circle having centre at (3, -4) and touching the line 5x + 12y- 12 = 0 is ______.

Q42. The equation of the circle circumscribing the triangle whose sides are the lines y = x + 2, 3y = 4x, 2y = 3x is   _______.
Given equation of line are:

Q43. An ellipse is described by using an endless string which is passed over two pins. If the axes are 6 cm and 4 cm, the length of the string and distance between the pins are _____ .

Q44. The equation of the ellipse having foci (0,1), (0, -1) and minor axis of length 1 is ___ .

Q45. The equation of the parabola having focus at (-1, -2) and the directrix x – 2y + 3 = 0 is______ .
Sol: Given that, focus at S(-l, -2) and directrix is x – 2y + 3 = 0

Q46. The equation of the hyperbola with vertices at (0, ±6) and eccentricity 5/3 ________ and its foci are _____    .

Objective Type Questions

Q47. The area of the circle centred at (1,2) and passing through (4, 6) is

Q48. Equation of a circle which passes through (3, 6) and touches the axes is

Q49. Equation of the circle with centre on the j-axis and passing through the origin and the point (2, 3) is

Q50. The equation of a circle with origin as centre and passing through the vertices of an equilateral triangle whose median is of length 3a is

Q51. If the focus of a parabola is (0, -3) and its directrix is y = 3, then its equation is

Q52. If the parabola y² = 4ax passes through the point (3, 2), then the length of its latus rectum is

Q53. If the vertex of the parabola is the point (-3, 0) and the directrix is the line x + 5 = 0, then its equation is
(a) y² = 8(x + 3)
(b) x² = 8(y + 3)
(c) y² = -8(x + 3)
(d) y² = 8(x + 5)

Q54. The equation of the ellipse whose focus is (1, -1), the directrix the line x-y-3 = 0 and eccentricity 1/2 is

Q55. The length of the latus rectum of the ellipse 3x² +y² = 12 is
(a) 4       
(b) 3       
(c) 8       
(d) 4/√3

NCERT Exemplar Problems Class 11 Mathematics

The post NCERT Exemplar Problems Class 11 Mathematics Chapter 11 Conic Sections appeared first on Learn CBSE.

NCERT Exemplar Problems Class 11 Mathematics Chapter 12 Introduction to Three Dimensional Geometry

Short Answer Type Questions

Q1. Locate the following points:

(i) (1,-1, 3),
(ii) (-1,2,4)               
(iii) (-2, -4, -7)
(iv) (-4,2, -5)
Sol: Given, coordinates
(i) (1,-1, 3),
(ii) (-1,2,4)
(iii) (-2, -4, -7)
(iv) (-4,2, -5)

Q2. Name the octant in which each of the following points lies.
(i) (1,2,3)             
(ii) (4,-2, 3)             
(iii) (4,-2,-5)              
(iv)(4,2,-5)
(v) (-4,2,5)           
(vi) (-3,-1,6)           
(vii) (2,-4,-7)
(viii) (-4, 2,-5)

Sol: We know that the sign of the coordinates of a point determine the octant in which the point lies. The following table shows the signs of the coordinates in eight octants.

Q3. Let A, B, C be the feet of perpendiculars from a point P on the x, y,z-axes respectively. Find the coordinates of A, B and C in each of the following where the point P is:
(i) (3,4,2)             
(ii) (-5,3,7)              
(iii) (4,-3,-5)
Sol: We know that, on x-axis, y, z = 0, on y-axis, x, z = 0 and on z-axis, x,y = 0. Thus, the feet of perpendiculars from given point P on the axis are as follows.

(i) A(3,0,0),5(0,4,0),C(0,0,2)
(ii) A(-5, 0, 0), B(0, 3, 0), C(0, 0, 7)
(iii) A(4, 0, 0), 5(0, -3, 0), C(0,0, -5)

Q4. Let A, B, C be the feet of perpendiculars from a point P on the xy, yz and zx- planes respectively. Find the coordinates of A, B, C in each of the following where the point P is
(i) (3,4,5)
(ii) (-5,3,7)
(iii) (4,-3,-5).
Sol: We know that, on xy-plane z = 0, on yz-plane, x = 0 and on zx-plane, y = 0. Thus, the coordinates of feet of perpendicular on the xy, yz and zx-planes from the given point are as follows:
(i) A(3,4,0), 5(0,4, 5), C(3,0,5)
(ii) A(-5, 3,0), 5(0, 3, 7), C(-5, 0, 7)
(iii) A(4, -3, 0), 5(0, -3, -5), C(4,0, -5)

Q5. How far apart are the points (2,0, 0) and (-3, 0, 0)?
Sol: Given points are A (2, 0, 0) and 5(-3,0, 0).
AB = |2 – (-3)| = 5

Q6. Find the distance from the origin to (6, 6, 7).
Sol: Distance form origin to the point (6, 6, 7)

Q8. Show that the point ,4(1, -1, 3), 6(2, -4, 5) and (5, -13, 11) are collinear.
Sol: Given points are ,4(1, -1, 3), 6(2, -4, 5) and C(5, -13, 11).

Q9. Three consecutive vertices of a parallelogram ABCD are .4(6, -2,4), 6(2,4, -8), C(-2, 2, 4). Find the coordinates of the fourth vertex.
Sol: Let the coordinates of the fourth vertex D be (x, y, z).

Q10 .Show that the triangle ABC with vertices .4(0,4,1), 6(2,3, -1) and C(4, 5,0) is right angled.
Sol: The vertices of ∆ABC are A(0,4, 1), 5(2, 3, -1) and C(4, 5, 0).

Q11. Find the third vertex of triangle whose centroid is origin and two vertices are (2,4,6) and (0, -2, -5).
Sol: Let the third or unknown vertex of ∆ABC be A(x, y, z).
Other vertices of triangle are 5(2,4, 6) and C(0, -2, -5).
The centroid is G(0, 0, 0).

Q12. Find the centroid of a triangle, the mid-point of whose sides are D (1,2, – 3), E(3,0, l)and F(-l, 1,-4).
Sol: Given that, mid-points of sides of AABC are D(l, 2, -3), E(3, 0, 1) and F(-l, 1,-4).

Q14. Three vertices of a Parallelogram ABCD are A(\, 2, 3), B(-A, -2, -1) and C(2, 3, 2). Find the fourth vertex
Sol: Let the fourth vertex of the parallelogram D(x, y, z).
Mid-point of BD

Q15. Find the coordinate of the points which trisect the line segment joining the points .A(2, 1, -3) and B(5, -8, 3).

Q16. If the origin is the centroid of a triangle ABC having vertices A(a, 1, 3), B(-2, b, -5) and C(4, 7, c), find the values of a, b, c.
Sol: Vertices of AABC are A(a, 1, 3), B(-2, b, -5) and C(4, 7, c).
Also, the centroid is G(0, 0, 0).

Q17. Let A(2, 2, -3), 5(5, 6, 9) and C(2, 7, 9) be the vertices of a triangle. The internal bisector of the angle A meets BC at the point Find the coordinates of D.

Long Answer Type Questions

Q18. Show that the three points A(2, 3, 4), 5(-l, 2, -3) and C(-4, 1, -10) are collinear and find the ratio in which Cdivides
Sol: Given points are A(2, 3, 4), B(-1, 2, -3) and C(-4,1,-10)

Q19. The mid-point of the sides of a triangle are (1, 5, -1), (0,4, -2) and (2, 3,4). Find its vertices. Also, find the centroid of the triangle.
Sol: Given that mid-points of the sides of AABC are D( 1, 5, -1), E(0, 4, -2) and F(2, 3,4).

Q20. Prove that the points (0, -1, -7), (2, 1, -9) and (6, 5, -13) are collinear. Find the ratio in which the first point divides the join of the other two.
Sol: Given points are 4(0, -1, -7), 8(2, 1, -9) and C(6, 5, -13).

Q21. What are the coordinates of the vertices of a cube whose edge is 2 units, one of whose vertices coincides with the origin and the three edges passing through the origin, coincides with the positive direction of the axes through the origin?
Sol: The coordinate of the cube whose edge is 2 units, are:
(2, 0, 0), (2,2, 0), (0, 2, 0), (0, 2,2), (0, 0,2), (2,0, 2), (0, 0, 0) and (2,2, 2)

Objective Type Questions

Q22. The distance of point P(3,4, 5) from the yz-plane is
(a) 3 units
(b) 4 units
(c) 5 units
(d) 550
Sol: (a) Given point is P{3,4, 5).
Distance of P from yz-plane = |x coordinate of P| = 3

Q23. What is the length of foot of perpendicular drawn from the point P(3,4, 5) on y-axis?

Q24. Distance of the point (3,4, 5) from the origin (0, 0, 0) is

Q25. If the distance between the points (a,0,1) and (0,1,2) is √27, then the value of a is
(a)     5                      
(b)     ± 5                   
(c)     -5                    
(d)   none of these

Q26. x-axis is the intersection of two planes
(a) xy and xz                                            
(b) yz and zx
(c) xy and yz                                            
(d) none of these
Sol: (a) We know that, on the xy and xz-planes, the line of intersection is x-axis.

Q27. Equation of Y-axis is considered as
(a) x = 0, y = 0                                         
(b) y = 0, z = 0
(c) z = 0, x = 0                                         
(d) none of these
Sol:(c) On the j-axis, x = 0 and z = 0.

Q28. The point (-2, -3, -4) lies in the
(a) First octant                                        
(b) Seventh octant
(c) Second octant                                   
(d) Eighth octant
Sol: (b) The point (-2, -3, -4) lies in seventh octant.

Q29. A plane is parallel to yz-plane so it is perpendicular to
(a) x-axis               
(b) y-axis                 
(c) z-axis                 
(d) none of these
Sol: (a) A plane parallel to yz-plane is perpendicular to x-axis.

Q30. The locus of a point for which y = 0, z = 0 is
(a)    equation of x-axis                         
(b)    equation of y-axis
(c)     equation at z-axis                         
(d)    none of these
Sol: (a) We know that, equation of the x-axis is: y = 0, z = 0 So, the locus of the point is equation of x-axis.

Q31. The locus of a point for which x = 0 is
(a)    xy-plane                                          
(b)    yz-plane
(c)     zx-plane                                        
 (d)    none of these
Sol: (b) On the yz-plane, x = 0, hence the locus of the point is yz-plane.

Q32. If a parallelepiped is formed by planes drawn through the points (5,8,10) and (3, 6, 8) parallel to the coordinate planes, then the length of diagonal of the parallelepiped is

Q33. L is the foot of the perpendicular drawn from a point P(3, 4, 5) on the xy-plane. The coordinates of point L are
(a)    (3,0,0)                                              
(b)    (0,4,5)
(c)     (3, 0, 5)                                            
(d)    none of these
Sol: (d) We know that on the xy-plane, z = 0.
Hence, the coordinates of the points L are (3,4, 0).

Q34. L is the foot of the perpendicular drawn from a point (3, 4, 5) on x-axis. The coordinates of L are
(a)    (3,0,0)                                              
(b)    (0,4,0)
(c)     (0, 0, 5)                                            
(d)    none of these
Sol: (a) On the x-axis, y = 0 and z = 0.
Hence, the required coordinates are (3, 0,0).

Fill in the Blanks Type Questions
Q35. The three axes OX, OY, OZ determine______ .
Sol: The three axes OX, OY and OZ determine three coordinate planes.

Q36. The three planes determine a rectangular parallelepiped which has____ of rectangular faces.

Q37. The coordinates of a point are the perpendicular distance from the _____ on the respective axes.
Sol: Given points

Q38. The three coordinate planes divide the space into _________parts.
Sol: Eight

Q39. If a point P lies in yz-plane, then the coordinates of a point on yz-plane is of the form_______.
Sol: We know that, on yz-plane, x = 0.So, the coordinates of the required point are (0, y, z).

Q40. The equation of yz-plane is ______ .
Sol: On yz-plane for any point x-coordinate is zero.
So, yz-plane is locus of point such that x = 0, which is its equation.

Q41. If the point P lies on z-axis, then coordinates of P are of the form_____.
Sol: On the z-axis, x = 0 and y = 0.
So, the required coordinates are of the form (0, 0, z).

Q42. The equation of z-axis, are ______.
Sol: Any point on the z-axis is taken as (0, 0, z).
So, for any point on z-axis, we have x = 0 and y = 0, which together represents its equation.
Q43. A line is parallel to xy-plane if all the points on the line have equal_________.
Sol: A line is parallel to xy-plane if each point P(x, y, z) on it is at same distance from xy-plane.
Distance of point P from xy plane is ‘z’
So, line is parallel to xy-plane if all the points on the line have equal z-coordinate.

Q44. A line is parallel to x-axis if all the points on the line have equal ______.
Sol: A line is parallel to x-axis if each point on it maintains constant distance from y-axis and z-axis.
So, each point has equal y and z-coordinates. .

Q45. x = a represents a plane parallel to .
Sol: Locus of point P(x, y, z) is x = a.
Therefore, each point P has constant x-coordinate.
Now, x is distance of point P from yz-plane.
So, here plane x = a is at constant distance ‘a’ from yz-plane and parallel to _yz-plane.

Q46. The plane parallel to yz-plane is perpendicular to_____ .
Sol: The plane parallel to yz-plane is perpendicular to x-axis.

Q47. The length of the longest piece of a string that can be stretched straight in a  rectangular room whose dimensions are 10, 13 and 8 units are______ .
Sol: Given dimensions are: a = 10, 6=13 andc = 8.
Required length of the string = yja² + b² + c² = ^100 + 169 + 64 = -7333

Q48. If the distance between the points (a, 2,1) and (1,-1,1) is 5, then a_______ .
Sol: Given points are (a, 2,1) and (1,-1,1).

Q49. If the mid-points of the sides of a triangle AB; BC; CA are D(l, 2, – 3), E( 3, 0, 1) and F(-l, 1, -4), then the centroid of the triangle ABC is________ .
Sol: Given that, mid-points of sides of AABC are D( 1, 2, -3), E(3, 0, 1) and F(-l, 1,-4).

Matching Column Type Questions

Q50. Match each item given under the column C₁ to its correct answer given under column C₂.

Sol: (a) In xy-plane, z-coordinate is zero.
(b) The point (2, 3,4) lies in 1st octant.
(c) Locus of the points having x-coordinate zero is yz-plane.
(d) A line is parallel to x-axis if and only if all the points on the line have equal y and z-coordinates.
(e)x = 0, y = 0 represent z-axis
(f) z = c represents the plane parallel to xy-plane.

(g) The plane x = a is parallel to yz-plane.
Plane y = b is parallel to xz-plane.
So,    planes x = a and y = b is line of intersection of these planes.
Now, line of intersection of yz-plane and xz-plane is z-axis.
So, line of intersection of planes x = a andy = b is line parallel to z-axis.
(h) Coordinates of a point are the distances from the origin to the feet of perpendicular from the point on the respective axis.
(i) A ball is the solid region in the space enclosed by a sphere.
(j) The region in the plane enclosed by a circle is known as a disc.
Hence, the correct matches are:
(a) – (iii), (b) – (i), (c) – (ii), (d) – (vi), (e) – (iv),
(f) – (v), (g) – (viii), (h) – (vii), (i) – (x), (j) – (ix),

NCERT Exemplar Problems Class 11 Mathematics

The post NCERT Exemplar Problems Class 11 Mathematics Chapter 12 Introduction to Three Dimensional Geometry appeared first on Learn CBSE.

NCERT Exemplar Problems Class 11 Mathematics Chapter 14 Mathematical Reasoning

Q1. Which of the following sentences are statements? Justify.
(i) A triangle has three sides.
(ii) O is a complex number.
(iii) Sky is red,
(iv) Every set is an infinite set.
(V) 15 +8>23
(vi) y+9=7
(vii) Where is your bag?
(viii) EVery square is a rectangle.
(ix) Sum of opposite angles of a cyclic quadrilateral is 1800.
(x) sin² x+cos² x=O
Sol: As we know, a statement is a sentence which is either true or false but not
both simultaneously.
(j) It is true statement.
(ii) It is true statement.
(iii) It is false statement.
(iv) It is false statement.
(y) It is false statement.
(vi) y +9 = 7
It is not considered as a statement, since the value of y is not given.
(vii) It is a question, so it is not a statement.
(viii) It is a true statement.
(ix) It is a true statement.
(x) It is a false statement.

Q2. Find the component statements of the following compound statements.
(i) Number 7 is prime and odd.
(ii) Chennai is in India and is the capital of Tamil Nadu.
(iii) The number loo is divisibLe by 3, 11 and 5.
(iv) Chandigarh is the capital of Irlaryana and U.P.
(y) √7 is a rational number or an irrational number.
(vi) O is less than every positive integer and every negative integer.
(vii) Plants use sunlight, water and carbon dioxide for photosynthesis.
(viii) Two lines in a plane either intersect at one point or they are parallel.
(ix) A rectangle is a quadrilateral or a 5-sided polygon.
Sol: (i) p: Number 7 is prime.
q: Number 7 is odd.
(ii) P: Chennai is in India.
q: Chennai is capital of Tamil Nadu.
(iii) p. 100 is divisible by 3.
q: 100 isdivisibleby 11.
r: 100 ¡s divisible by 5.
(iv) p. Chandigarh is capital of Haryana.
q: Chandigarb is capital of UP
(v) p: √7 is a rational number.
q: √7 is an irrational number.
(vi) p: 0 is less than every positive integer.
q: O is less than every negative integer.
(vii) p: Plants use sunlight for photosynthesis.
q: Plants use water for photosynthesis.
q:- Plants use carbon dioxide for photosynthesis.
(viii) p: Two lines in a plane intersect at one point.
q: Two lines ¡n a plane are parallel.
(ix) p: A rectangle is a quadrilateral.
q. A rectangle is a 5-sided polygon.

Q3. Write the component statements of the following compound statements and
check whether the compound statement is true or false.
(i) 57 is divisible by 2 or 3.
(ii) 24 is a multiple of 4 and 6.
(iii) All living things have two eyes and two legs.
(iv) 2 is an even number and a prime number.
Sol: (i) Here component statements are:
p: 57 is divisible by 2. [false]
q: 57 is divisible by 3. [true]
Given compound statement is of the form ‘pvq’.
Since, the statement ‘pvq’ has the truth value T whenever either p or q
or both have the truth value T.
So, it is true statement as 57 is divisible by 3.
(ii) Here component statements are: p: 24 is multiple of 4. q: 24 is multiple of 6.
Given compound statement is of the form ‘p ^ q’
Since, the statement ‘p A q’ has the truth value T whenever bothp and q have the truth value T.
So, it is a true statement as 24 is divisible by 4 and 6.
(iii) Here component statements are:
p: All living things have two eyes. [false]
q: All living things have two legs. [false]
Given compound statement is of the form ‘p ^q’
It is a false statement. Since ‘p ^ q’ has truth value F whenever either p or q or both have the truth value F
(iv) Here component statements are:
p: 2 is an even number. [true]
q: 2 is a prime number. [true]
Given compound statement is of the form ‘p ^ q’.
It is a true statement. Since ‘p ^ q’ has truth value T whenever both p and q or both have the truth value T.

Q4. Write the negative on the following simple statements.
(i) The number 17 is prime.
(ii) 2 + 7 = 6.
(iii) Violets are blue.
(iv) √5 is a rational number.
(v) 2 is not a prime number.
(vi) Every real number is an irrational number.
(vii) Cow has four legs.
(viii) A leap year has 366 days.
(ix) All similar triangles are congruent.
(x) Area of a circle is same as the perimeter of the circle.
Sol: (i) The number 17 is not prime.
(ii) 2 + 7≠6.
(iii) Violets are not blue.
(iv) √5 is not a rational number.
(v) 2 is a prime number.
(vi) Every real number is not an irrational number.
(vii) Cow does not have four legs.
(viii) A leap year does not have 366 days.
(ix) There exist similar triangles which are not congruent.
(x) Area of a circle is not same as the perimeter of the circle

Q5. Translate the following statements into symbolic form.
(i) Rahul passed in Hindi and English.
(ii) x and y are even integers.
(iii) 2, 3 and 6 are factors of 12.
(iv) Either x or x + 1 is an odd integer.
(v) A number is either divisible by 2 or 3.
(vi) Either x = 2 or x = 3 is a root of 3x² – x – 10 = 0
(vii) Students can take Hindi or English as an optional paper.
Sol: (i) p: Rahul passed in Hindi.
q: Rahul passed in English. p ∧ q: Rahul passed in Hindi and English.
(ii) p: x is even integers. . q: y is even integers.
p∧q: x andy are even integers.
(iii) p: 2 is factor of 12. q: 3 is factor of 12. r: 6 is factor of 12.
p ∧ q ∧ r: 2, 3 and 6 are factors of 12
(iv) p: x is an odd integer.
q: (x + 1) is an odd integer. p v q: Either x or (x + 1) is an odd integer.
(v) p: A number is divisible by 2. q: A number is divisible by 3.
pv q: A number is either divisible by 2 or 3.
(vi) p: x = 2 is a root of 3×2 – x – 10 = 0. q: x = 3 is a root of 3×2 – x – 10 = 0
p v q: Either x = 2orx = 3isa root of 3×2 – x – 10 = 0
(vii) p: Students can take Hindi as an optional paper. q: Students can take English as an optional paper.
p v q: Students can take Hindi or English as an optional paper.

Q6. Write down the negation of following compound statements.
(i) All rational numbers are real and complex.
(ii) All real numbers are rationals or irrationals.
(iii) x = 2 and x = 3 are roots of the quadratic equation x² -5x +6 = 0
(iv) A triangle has either 3-sides or 4-sides.
(v) 35 is a prime number or a composite number.
(vi) All prime integers are either even or odd.
(vii) |x| is equal to either x or -x.
(viii) 6 is divisible by 2 and 3.
Sol. (i) Let p: All rational numbers are real.
q: All rational numbers are complex.
~ p: All rational numbers are not real.
~ q ; All rational numbers are not complex.
Then, the negation of the given compound statement is:
~ (p ∧ q): All rational numbers are not real or not complex.
[~(p ∧ q) = ~p v ~q]
(ii) Let p: All real numbers are rationals. q: All real numbers are irrationals.
Then, the negation of the given compound statement is:
~ (p v q): All real numbers are not rational and all real numbers are not irrational. [~(p v q) = ~p ∧ ~ q]
(iii) Let p ; x = 2 is root of quadratic equation x² – 5x + 6 = 0. q: x = 3 is root of quadratic equation x² – 5x + 6 = 0.
Then, the negation of the given compound statement is:
~ (p ∧  q) : x = 2 is not a root of quadratic equation x²– 5x + 6 = 0 or x = 3 is not a root of the quadratic equationx² – 5x + 6 = 0.
(iv) Let p: A triangle has 3-sides. q: A triangle has 4-sides.
Then, the negation of the given compound statement is:
~ (p v q): A triangle has neither 3-sides nor 4-sides.
(v) Let p: 35 is a prime number. q: 35 is a composite number.
Then, the negation of the given compound statement is:
~ (p v q): 35 is not a prime number and it is not a composite number.
(vi) Let p: All prime integers are even. q: All prime integers are odd.
Then, the negation of the given compound statement is given by
~(p v q): All prime integers are not even and all prime integers are not odd.
(vii) Let p:|x| is equal to x. q: |x| is equal to —x.
Then, the negation of the given compound statement is:
~ (p v q): |x| is not equal to JC and it is not equal to —x.
(viii) Let p: 6 is divisible by 2. q: 6 is divisible by 3.
Then, the negation of the given compound statement is:
~ (p∧q): 6 is not divisible by 2 or it is not divisible by 3

Q7. Rewrite each of the following statements in the form of conditional statements.
(i) The square of an odd number is odd.
(ii) You will get a sweet dish after the dinner.
(iii) You will fail, if you will not study.
(iv) The unit digit of an integer is 0 or 5, if it is divisible by 5.
(v) The square of a prime number is not prime.
(vi) 2b = a + c, if a, b and c are in AP.
Sol: (i) If the number is odd number, then its square is odd number.
(ii) It you take the dinner, then you will get sweet dish.
(iii If you will not study, then you will fail.
(iv) If an integer is divisible by 5, then its unit digits are 0 or 5.
(v) If the number is prime, then its square is not prime.
(vi) If a, b and c are in AP, then 2b = a + c.

Q8. Form the biconditional statement p⟷q, where
(i) p: The unit digits of an integer is zero.
q: It is divisible by 5.
(ii) p: A natural number is odd.
q: Natural number is not divisible by 2.
(iii) p: A triangle is an equilateral triangle.
q: All three sides of a triangle are equal.
Sol:(i) p ⟷ q: The unit digit of on integer is zero, if and only if it is divisible by 5.
(ii) p ⟷ q: A natural number is odd if and only if it is not divisible by 2.
(iii) p ⟷q: A triangle is an equilateral triangle if and only if all three sides of triangle are equal.

Q9. Write down the contra positive of the following statements.
(î) lf x =y and y=3,then x = 3.
(ii) If n is a natural number, then n is an integer.
(iii) If all three sides ola triangle are equal, then the triangle is equilateral.
(iv) If x andy are negative integers, then .ty is positive.
(v) If natural number n is divisible by 6, then n is divisible by 2 and 3.
(vi) Jf it snows, then the weather will be cold.
(vii) lix is a real number such that O <x < 1, then x2 < 1
Sol: (i) If x ≠ 3, then x ≠y or y ≠ 3.
(ii) 1f n is not an integer, then it is not a natural number.
(iii) If the triangle is not equilateral, then all three sides of the triangle are not equal.
(iv) If xv is not positive integer, then either x or y is not negative integer.
(v) If natural number n is not divisible by 2 or 3, then n is not divisible by 6.
(vi) The weather will not be cold, if it does not snow.
(vii) lf x² is not less than I, thenx is not a real number such that O <x <1.

Q10. Write down the converse of following statements.
(i) If a rectangle lR’ is a square, then R is a rhombus.
(ii) If today is Monday, then tomorrow is Tuesday.
(iii) If you go to Agra, then you must visit Taj Mahal.
(iv) If sum of squares of two sides of a triangle is equal to the square of third side of a triangle, then the triangle is right angled.
(v) If all three angles of a triangle are equal, then the triangle is equilateral.
(vi) If x : y = 3 : 2, then 2x = 3y.
(vii) If S’ is a cyclic quadrilateral, then the opposite angles of S are supplementary.
(viii) If x is zero, then x is neither positive nor negative.
(ix) If two triangles are similar, then the ratio of their corresponding sides are equal.
Sol: (i) If the rectangle ‘S’ is rhombus, then it is square.
(ii) It tomorrow is Tuesday, then today is Monday.
(iii) If you must visit Taj Mahal, you go to Agra.
(iv) If the triangle is right angle, then the sum of squares of two sides of a triangle is equal to the square of third side.
(v) If the triangle is equilateral, then all three angles of triangle are equal.
(vi) If 2x = 3y, thenx :y = 3:2
(vii) If the opposite angles of a quadrilateral are supplementary, then S is cyclic.
(viii) If x is neither positive nor negative, then x is 0.
(ix) If the ratio of corresponding sides of two triangles are equal, then triangles are similar

Q11. Identify the quantifiers in the following statements.
(i) There exists a triangle which is not equilateral.
(ii) For all real numbers x and y, xy= yx.
(iii) There exists a real number which is not a rational number.
(iv) For every natural number x, x + 1 is also a natural number.
(v) For all real numbers x with x > 3, x² is greater than 9.
(vi) There exists a triangle which is not an isosceles triangle.
(vii) For all negative integers x, x³ is also a negative integers.
(viii) There exists a statement in above statements which is not true.
(ix) There exists an even prime number other than 2.
(x) There exists a real number x such that x² + 1 = 0.
Sol: Quantifier are the phrases like ‘There exists’ and ‘For every1, ‘For all’ etc.
(i) There exists
(ii) For all
(iii) There exists
(iv) For every
(v) For all
(vi) There exists
(vii) For all (viii) There exists
(ix) There exists
(x) There exists

Q12. Prove by direct method that for any integer ‘n’ ,n³ – n is always even.

Q13. Check validity of the following statements.
(i) p: 125 is divisible by 5 and 7.
(ii) q: 131 is a multiple of 3 or 11.
Sol: (i) We have,P : 125 is divisible by 5 and 7.
Let q: 125 is divisible by 5.
r: 125 is divisible by 7. q is true, r is false.
=> q ⋀ r is false.
[since, p ⋀ q has the truth value F (false) whenever eitherp or q or both have the truth value F]
Hence, p is not valid.
(ii) We have,  p: 131 is a multiple of 3 or 11.
Let q: 131 is multiple of 3.
r: 131 is a multiple of 11.
p is true, r is false.
=> p v r is true.
[since, p v q has the truth value T (true) whenever either p or q or both have the truth value T]
Hence, q is valid.

Q14. Prove the following statement by contradiction method.
p: The sum of an irrational number and a rational number is irrational.

Q15. Prove by direct method that for any real number x, y if x = y, then x ²=y²

Sol: Let p: x = y; x, y∈ R
On squaring both sides, we get
x² =y² :q
p ⟹q
Hence, proved.

Q16. Using contra positive method prove that, if n² is an even integer, then n is also an even integer.
Sol: Let p: n² is an even integer. q: n is also an even integer.
Let ~p is true i.e., n is not an even integer.
=> n² is not an even integer. [Since square of an odd integer is odd]
=> ~ p is true.
Therefore, ~q is true which provides that ~p is true.
Hence proved.

Objective Type Questions
Q17. Which of the following is a statement?
(a) x is a real number (b) Switch off the fan
(c) 6 is a natural number (d) Let me go
Sol: (c) As we know that a statement is a sentence which is either true or false.
6 is a natural number; this is true.
Hence, it is a statement.

Q18. Which of the following is not a statement.
(a) Smoking is injurious to health
(b) 2 + 2 = 4
(c) 2 is the only even prime number
(d) Come here
Sol: (d) No sentence can be called a statement, if it is an order. So, ‘Come here’ is not a statement.

Q19. The connective in the statement ‘2 + 7>9or2 + 7<9’is
(a) and
(b) or
(c) >
(d) <
Sol: (b) In ‘2 + 7 > 9 or 2 + 7 < 9’, or is the connective.

Q20. The connective in the statement “Earth revolves round the Sun and Moon is a satellite of earth” is
(a) or
(b) Earth
(c) Sun
(d) and
Sol: (d) Connective word is ‘and’.

Q21. The negation of the statement “A circle is an ellipse” is
(a) An ellipse is a circle
(b) An ellipse is not a circle
(c) A circle is not an ellipse
(d) A circle is an ellipse
Sol: (c) Let p: A circle is an ellipse.
~p: A circle is not an ellipse.

Q22. The negation of the statement “7 is greater than 8” is
(a) 7 is equal to 8
(b) 7 is not greater than 8
(c) 8 is less than 7
(d) None of these
Sol: (b) Letp: 7 is greater than 8.
~p: 7 is not greater than 8

Q23. The negation of the statement “72 is divisible by 2 and 3” is
(a) 72 is not divisible by 2 or 72 is not divisible by 3
(b) 72 is not divisible by 2 and 72 is not divisible by 3
(c) 72 is divisible by 2 and 72 is not divisible by 3
(d) 72 is not divisible by 2 and 72 is divisible by 3
Sol: (a) We have, p: 72 is divisible by 2 and 3.
Let q: 72 is divisible by 2.
r: 72 is divisible by 3.
~q: 72 is not divisible by 2.
~r. 72 is not divisible by 3.
~{q ⋀f ) -~q v ~r
⟹ 72 is not divisible by 2 or 72 is not divisible by 3.

Q24. The negation of the statement “Plants take in C0₂ and give out 0₂” is
(a) Plants do not take in C0₂ and do not given out 0₂
(b) Plants do not take in C0₂ or do not give out 0₂
(c) Plants take is C0₂ and do not give out 0₂
(d) Plants take in C0₂ or do not give out 0₂
Sol: (b) Now, p: Plants take in C0₂ and give out 0₂.
Let q: Plants take in C0₂.
r: Plants give out 0₂.
~q: Plants do not take in C0₂.
~r: Plants do not give out 0₂.
~(q ∧ r): Plants do not take in C0₂ or do not give out 0₂.

Q25. The negative of the statement “Rajesh or Rajni lived in Bangalore” is
(a) Rajesh lives in Bangalore and Rajni did not live in Bangalore
(b) Rajesh did not live in Bangalore and Rajni did not live in Bangalore
(c) Rajesh did not live in Bangalore or Rajni did not live in Bangalore
Sol: (c) We have, p: Rajesh or Rajni lived in Bangalore.
and                q: Rajesh lived in Bangalore.
r: Rajni lived in Bangalore.
~q: Rajesh did not live in Bangalore.
~r. Rajni did not live in Bangalore.
~ (q v r): Rajesh did not live in Bangalore and Rajni did not live in Bangalore.

Q26. The negation of the statement “101 is not a multiple of 3” is
(a) 101 is a multiple of 3
(b) 101 is a multiple of 2
(c) 101 is an odd number                     
(d) 101 is an even number
Sol: (a) Let p: 101 is not a multiple of 3.
~p: 101 is a multiple of 3,

Q27. The contra positive of the statement
“If 7 is greater than 5, then 8 is greater than 6” is
(a) If 8 is greater than 6, then 7 is greater than 5
(b) If 8 is not greater than 6, then 7 is greater than 5
(c) If 8 is not greater than 6, then 7 is not greater than 5
(d) If 8 is greater than 6, then 7 is not greater than 5
Sol: (c) Letp: 7 is greater than 5.
and q: 8 is greater than 6.
∴P→ q
~p: 7 is not greater than 5.
~q: 8 is not greater than 6.
(~q) → (~p) i.e., if 8 is not greater than 6, then 7 is not greater than 5.

Q28. The converse of the statement “If x > y, then x + a > y + a” is
(a)    If x <y, then x + a <y + a      
(b) If x + a >y + a, then x>y
(c)    If x <y, then x+ a <y + a        
(d) If x >y, then x + a<y+ a
Sol: (b) Let p: x >y
q:x + a>y + a
P ⟶ q
Converse of the above statement is:
q⟶P
i.e., If x + a > y + a, then x>y

Q29. The converse of the statement “If sun is not shining, then sky is filled with clouds” is
(a) If sky is filled with clouds, then the Sun is not shining
(b) If Sun is shining, then sky is filled with clouds
(c) If sky is clear, then Sun is shining
(d) If Sun is not shining, then sky is not filled with clouds
Sol: (a) Let p: Sun is not shining.
and q:Sky is filled with clouds.
Converse of the above statement p → q is q → p.
If sky is filled with clouds, then the Sun is not shining.

Q30. The contra positive of the statement “If p, then q” is
(a) if q, then p                                        
(b) if p, then ~q
(c) if ~q, then ~p                                  
(d) if ~p, then ~q
Sol:(c) p → q                                           ‘
If p, then q
Contra positive of the statement p → q is (~q) →(~ p).
If ~q, then ~p.

Q31. The statement “If x² is not even, then x is not even” is converse of the statement
(a) If x² is odd, then x is even
(b) If x is not even, then x² is not even
(c) If x is even, then x² is even
(d) If x is odd, then x² is even
Sol: (b) Let p: x² is not even.
and q: x is not even.
Converse of the statement p →q is q → p. i.e.,
If x is not even, then x² is not even.

Q32. The contra positive of statement ‘If Chandigarh is capital of Punjab, then Chandigarh is in India’ is
(a) If Chandigarh is not in India, then Chandigarh is not the capital of Punjab
(b) If Chandigarh is in India, then Chandigarh is Capital of Punjab
(c) If Chandigarh is not capital of Punjab, then Chandigarh is not capital of India
(d) If Chandigarh is capital of Punjab, then Chandigarh is not is India
Sol: (a) Let p: Chandigarh is capital of Punjab.
and q: Chandigarh is in India.
~ p: Chandigarh is not capital of Punjab.
~q: Chandigarh is not in India.
Contra positive of the statement p → q
if (~q), then (~p).
It Chandigarh is not in India, then Chandigarh is not the capital of Punjab.

Q33. Which of the following is the conditional p → q?
(a) q is sufficient for p                         
(b) p is necessary for q
(c) p only if q                                         
(d) if q then p
Sol: (c) ‘p → q is same as ‘p only if q’.

Q34. The negation of the statement “The product of 3 and 4 is 9” is
(a) it is false that the product of 3 and 4 is 9
(b) the product of 3 and 4 is 12
(c) the product of 3 and 4 is not 12
(d) it is false that the product of 3 and 4 is not 9
Sol: (a) The negation of the above statement is ‘It is false that the product of 3 and 4 is 9’.

Q35. Which of the following is not a negation of “A nature number is greater than zero”
(a) A natural number is not greater than zero
(b) It is false that a natural number is greater than zero
(c) It is false that a natural number is not greater than zero
(d) None of the above
Sol: (c) The false negation of the given statement is “It is false that a natural number is not greater than zero”.

Q36. Which of the following statement is a conjunction?
(a) Ram and Shyam are friends
(b) Both Ram and Shyam are tall
(c) Both Ram and Shyam are enemies
(d) None of the above
Sol: (d) If two simple statements p and q are connected by the word ‘and’, then the resulting compound statement p and q is called a conjunction ofp and q. Here, none of the given statement is conjunction.

Q37. State whether the following sentences are statements or not.
(i) The angles opposite to equal sides of a triangle are equal.
(ii) The moon is a satellites of Earth.
(iii) May God bless you.
(iv) Asia is a continent.
(v) How are you? ,
Sol: (i) It is a statement.
(ii) It is a statement,
(iii) It is not a statement, since it is an exclamations.
(iv) It is a statement.
(v) It is not a statement, since it is a question.

NCERT Exemplar Problems Class 11 Mathematics

The post NCERT Exemplar Problems Class 11 Mathematics Chapter 14 Mathematical Reasoning appeared first on Learn CBSE.

NCERT Exemplar Problems Class 11 Mathematics Chapter 15 Statistics

Short Answer Type Questions
Q1. Find the mean deviation about the mean of the distribution:

Q2. Find the mean deviation about the median of the following distribution:

Q3. Calculate the mean deviation about the mean of the set of first n natural numbers when n is an odd number.
Sol: Consider first natural number when n is an odd i.e., 1, 2, 3,4,… , n [odd].

Q4. Calculate the mean deviation about the mean of the set of first n natural numbers when n is an even number.
Sol: Consider first n natural number, when n is even i.e., 1, 2, 3,4..n.

Q5. Find the standard deviation of the first n natural numbers.

Q6. The mean and standard deviation of some data for the time taken to complete . a test are calculated with the following results:
Number of observations = 25, mean = 18.2 seconds, standard deviation = 3.25 s.

Q8. Two sets each of 20 observations, have the same standard derivation 5. The first set has a mean 17 and the second a mean 22. Determine the standard deviation of the set obtained by combining the given two sets.

Q9. The frequency distribution:

where A is a positive integer, has a variance of 160. Determine the value of A.

Q10. For the frequency distribution:

Find the standard deviation.

Q11. There are 60 students in a class. The following is the frequency distribution of the marks obtained by the students in a test:

where x is a positive integer. Determine the mean and standard deviation of the marks.

Q12. The mean life of a sample of 60 bulbs was 650 hours and the standard deviation was 8 hours. A second sample of 80 bulbs has a mean life of 660 hours and standard deviation 7 hours. Find the overall standard deviation.

Q13. Mean and standard deviation of 100 items are 50 and 4, respectively. Then find the sum of all the item and the sum of the squares of the items.

Q14. If for a distribution Σ (x -5)= 3,Σ (x -5)²= 43 and the total number of item is 18, find the mean and standard deviation.
Sol: Given, n = 18, Σ (x – 5) = 3 and Σ (x – 5)² = 43

Q15. Find the mean and variance of the frequency distribution given below:

Long Answer Type Questions
Q16. Calculate the mean deviation about the mean for the following frequency distribution:

Q17. Calculate the mean deviation from the median of the following data

Q18. Determine the mean and standard deviation for the following distribution:

Q19. The weights of coffee in 70 jars are shown in the following table:

Determine variance and standard deviation of the above distribution.

Q20. Determine mean and standard deviation of first n terms of an A.P. whose first term is a and common difference is d.

Q21. Following are the marks obtained, out of 100, by two students Ravi and Hashinain 10 tests.

Who is more intelligent and who is more consistent?

Q22. Mean and standard deviation of 100 observations were found to be 40 and 10,respectively. If at the time of calculation two observations were wrongly taken as 30 and 70 in place of 3 and 27 respectively, find the correct standard deviation.

Q23. While calculating the mean and variance of 10 readings, a student wrongly used the reading 52 for the correct reading 25. He obtained the mean and variance as 45 and 16 respectively. Find the correct mean and the variance.

Objective Type Questions
Q24. The mean deviation of the data 3,10, 10,4, 7, 10, 5 from the mean is (a) 2 (b) 2.57 (c) 3 (d) 3.75
Sol: (b) Given, observations are 3, 10, 10, 4, 7, 10 and 5.

Q26. When tested, the lives (in hours) of 5 bulbs were noted as follows: 1357, 1090, 1666, 1494, 1623 The mean deviations (in hours) from their mean is (a) 178 (b) 179 (c) 220 (d) 356

Q27. Following are the marks obtained by 9 students in a mathematics test:
50, 69,20, 33, 53, 39,40, 65, 59 The mean deviation from the median is:
(a) 9 (b) 10.5 (c) 12.67 (d) 14.76
Sol: (c) Since, marks obtained by 9 students in Mathematics are 50,69,20,33,53, 39,40, 65 and 59.
Rewrite the given data in ascending order.
20, 33, 39,40, 50, 53, 59, 65, 69,
Here, n = 9 [odd]

Q30. The mean of 100 observations is 50 and their standard deviation is 5. The sum of all squares of all the observations is
(a) 50000 (b) 250000 (c) 252500 (d) 255000

Q31. Let a, b, c, d, e be the observations with mean m and standard deviation V. The standard deviation of the observations a + k,b + k,c + k,d+k,e + k is

Q34. Standard deviations for first 10 natural numbers is
(a) 5.5 (b) 3.87 (c) 2.97 (d) 2.87

Q35. Consider the numbers 1,2, 3,4, 5, 6, 7, 8,9,10. If 1 is added to each number, the variance of the numbers so obtained is
(a) 6.5 (b) 2.87 (c) 3.87 (d) 8.25
Sol: (d) Given numbers are 1, 2, 3,4, 5, 6, 7, 8, 9 and 10
If 1 is added to each number, then observations will be 2, 3,4, 5, 6,7, 8, 9, 10 and 11.

Q36. Consider the first 10 positive integers. If we multiply each number by -1 and then add 1 to each number, the variance of the numbers so obtained is (a) 8.25 (b) 6.5 (c) 3.87 (d) 2.87
Sol: (a) Since, the first 10 positive integers are 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10.
On multiplying each number by -1, we get
-1, -2, -3, -4, -5, -6, -7, -8, -9, -10 On adding 1 in each number, we get
0, -1, -2, -3, -4, -5, -6, -7, -8, -9

Q38. Coefficient of variation of two distributions are 50 and 60, and their arithmetic means are 30 and 25 respectively. Difference of their standard deviation is
(a) 0 (b) 1 (c) 1.5 (d) 2.5

Q39. The standard deviation of some temperature data in °C is 5. If the data were converted into °F, the variance would be
(a) 81 (b) 57 (c) 36 (d) 25

Fill in the Blanks

Q43. The standard deviation of a data is _____ of any change in origin, but is ________ on the change of scale.
Sol: The standard deviation of a data is independent of any change in origin but is dependent of charge of scale.
Q44. The sum of the squares of the deviations of the values of the variable is ________ when taken about their arithmetic mean.
Sol: The sum of the squares of the deviations of the values of the variable is minimum when taken about their arithmetic mean.
Q45. The mean deviation of the data is ________ when measured from the median.
Sol: The mean deviation of the data is least when measured from the median.
Q46. The standard deviation is________ to the mean deviation taken from the arithmetic mean.
Sol: The standard deviation is greater than or equal to the mean deviation taken from the arithmetic mean.

NCERT Exemplar Problems Class 11 Mathematics

The post NCERT Exemplar Problems Class 11 Mathematics Chapter 15 Statistics appeared first on Learn CBSE.

NCERT Exemplar Problems Class 11 Mathematics Chapter 16 Probability

Short Answer Type Questions 

Q1. If the letters of the word ALGORITHM are arranged at random in a row what is the probability the letters GOR must remain together as a unit?
Sol: We have word ALGORITHM Number of letters = 9

Q2. Six new employees, two of whom are married to each other, are to be assigned six desks that are lined up in a row. If the assignment of employees to desks is made randomly, what is the probability that the married couple will have nonadjacent desks?
Sol: Six employees can be arranged in 6! ways.
n(S) = 6!
Two adjacent desks for married couple can be selected in 5 ways viz.,(l, 2), (2, 3), (3,4), (4, 5), (5,6).
This couple can be arranged in the two desks in 2! ways.
Other four persons can be arranged in 4! ways.
So, number of ways in which married couple occupy adjacent desks
= 5×2! x4! =2×5!
So, number of ways in which married couple occupy non-adjacent desks = 6! – 2 x 5! = 4 x 5! = n(E)

Q3. Suppose an integer from 1 through 1000 is chosen at random, find the probability that the integer is a multiple of 2 or a multiple of 9.
Sol: We have integers 1,2, 3,…1000
We have integers 1,2, 3,…1000
n(S) = 1000
Number of integers which are multiple of 2 = 500 Let the number of integers which are multiple of 9 be n.
nth term = 999 =>   9 + (n -1)9 = 999
=>             9 + 9n – 9 = 999
=>          n = 111
From 1 to 1000, the number of multiples of 9 is 111.
The multiple of 2 and 9 both are 18, 36,…, 990.
Let m be the number of terms in above series.
.’.               mth term = 990
=>             18 + (m- 1)18 = 990
=>             18+18m-18 = 990
=>        m = 55
Number of multiples of 2 or 9 = 500 +111-55 = 556 = n(E)

Q4. An experiment consists of rolling a die until a 2 appears.
(i) How many elements of the sample space correspond to the event that the 2 appears on the Ath roll of the die?
(ii) How many elements of the sample space correspond to the event that the 2 appears not later than the Ath roll of the die?
Sol: Number of outcomes when die is thrown is ‘6’.
(i) If 2 appears on the Ath roll of the die.
So, first (k -1) roll have 5 outcomes each and Kth roll results 2
Number of outcomes = 5^k-1

(ii) If we consider that 2 appears not later than K th roll of the die, then 2 comes before Ath roll.
If 2 appears in first roll, number of ways = 1 If 2 appears in second roll, number of ways
= 5 x 1 (as first roll does not result in 2)
If 2 appears in third roll, number of ways
= 5 x 5 x 1 (as first two rolls do not result in 2)
Similarly if 2 appears in (k – l)th roll, number of ways = [5x5x5… (k- 1) times] x 1 = 5^k-1 Possible outcomes if 2 appears before kth roll = 1 +5 + 5² + 5³+ … +5^k-l

Q5. A die is loaded in such a way that each odd number is twice as likely to occur as each even number. Find P(G), where G is the event that a number greater than 3 occurs on a single roll of the die.
Sol: If is given that 2 x Probability of even number = Probability of odd

Q6. In a large metropolitan area, the probabilities are .87, .36, .30 that a family (randomly chosen for a sample survey) owns a colour television set, a black and white television set, or both kinds of sets. What is the probability that a family owns either anyone or both kinds of sets?
Sol: Let C be the even that family own colour television set and B be the event that family owns a black and white television set It is given that,
P(C) = 0.87, P{B) = 0.36 and P(C∩B) = 0.30 We have to find probability that a family owns either anyone or both kind of sets i.e., P(B ∪ C)
Now, P(B∪C) = P(B) + P(C)-P(C∩ B)
= 0.87 + 0.36-0.30= 0.93

Q7. If A and B are mutually exclusive events, P(A) =35 and P(B) = 0.45, find
(a) P(A’)
(b) P(B’)
(c) P(A∪ B)
(d) P(A∩ B)
(e) P(A∪ B’)                                           
(f) P(A’∩B’)

Q8. A team of medical students doing their internship have to assist during surgeries at a city hospital. The probabilities of surgeries rated as very complex, complex, routine, simple or very simple are respectively, 0.15,0.20, 0.31, 0.26, .08. Find the probabilities that a particular surgery will be rated
(a) complex or very complex;
(b) neither very complex nor very simple;
(c) routine or complex
(d) routine or simple

Q9. Four candidates A, B, C, ZJhave applied for the assignment to coach a school cricket team. If A is twice as likely to be selected as B, and B and C are given about the same chance of being selected, while C is twice as likely to be selected as D, what are the probabilities that
(a) C will be selected? (b) A will not be selected?
Sol: It is given that A is twice as likely to be selected as B.
P(A) = 2P(B)
B and C are given about the same chance of being selected.
P(B) = P(C)
C is twice as likely to be selected as D.
P(C) = 2 P(D)

Q10. One of the four persons John, Rita, Aslam or Gurpreet will be promoted next month. Consequently the sample space consists of four elementary outcomes S = {John promoted, Rita promoted, Aslam promoted, Gurpreet promoted}. You are told that the chances of John’s promotion is same as that of Gurpreet, Rita’s chances of promotion are twice as likely as Johns. Aslam’s chances are four times that of John.
(a) Determine
P(John promoted)
P(Rita promoted)
P(Aslam promoted)
P(Gurpreet promoted)
(b) If A = {John promoted or Gurpreet promoted}, find P(A).
Sol: Let Event: J = John promoted
R = Rita promoted
A = Aslam promoted
G = Gurpreet promoted
Given sample space, S = {John promoted, Rita promoted, Aslam promoted, Gurpreet promoted}
i.e. S={J,R,A,G)
It is given that, chances of John’s promotion is same as that of Gurpreet.
P(J) = P(G)
Rita’s chances of promotion are twice as likely as John.
P(R) = 2P(J)
And Aslam’s chances of promotion are four times that of John.
P(A) = 4P(J)
Now, P(J) + P(R) + P(A) + P(G) = 1 => P(J) + 2P(J) + 4P(J) + P(J) = 1
=> 8P(J) = 1
P(J) = 1/8

Q11. The accompanying Venn diagram shows three events, A, B, and C, and also the probabilities of the various intersections (for instance, P(A∩B) = .07).

Q12. One urn contains two black balls (labelled Bx and B2) and one white ball. A second urn contains one black ball and two white balls (labelled W₁ and W₂). Suppose the following experiment is performed. One of the two urns is chosen at random. Next a ball is randomly chosen from the urn. Then a second ball is chosen at random from the same urn without replacing the first ball.
(a) Write the sample space showing all possible outcomes
(b) What is the probability that two black balls are chosen?
(c) What is the probability that two balls of opposite colour are chosen?
Sol:It is given that one of the two urn is chosen, then a ball is randomly chosen
from the urn, then a second ball is chosen at random from the same urn without replacing the first ball.

Q13. A bag contains 8 red and 5 white balls. Three balls are drawn at random. Find the Probability that
(a) All the three balls are white
(b) All the three balls are red
(c) One ball is red and two balls are white
Sol: Number of red balls = 8
and number of white balls = 5

Q15. A card is drawn from a deck of 52 cards. Find the probability of getting a king or a heart or a red card.
Sol: Number of cards = 52 .-.            n(S) = 52
4 king + 13 heart + 26 red – 13 – 2 = 28 = n{E)
.’.             Required probability = 28/52 = 7/13

Q17. Determine the probability p, for each of the following events.
(a) An odd number appears in a single toss of a fair die.
(b) At least one head appears in two tosses of a fair coin.
(c) The sum of 6 appears in a single toss of a pair of fair dice.
Sol: (a) When a die is thrown the possible outcomes are
S = {1, 2, 3,4, 5, 6} out of which 1, 3, 5 are odd,

Objective type Questions

Q18. In a non-leap year, the probability of having 53 Tuesdays or 53 Wednesdays is

Q19. Three numbers are chosen from 1 to 20. Find the probability that they are not consecutive

Q20. While shuffling a pack of 52 playing cards, 2 are accidentally dropped. Find the probability that the missing cards to be of different colours

Q21. Seven persons are to be seated in a row. The probability that two particular persons sit next to each other is

Q22. Without repetition of the numbers, four digit numbers are formed with the numbers 0, 2, 3, 5. The probability of such a number divisible by 5 is

Q23. If A and B are mutually exclusive events, then

Q24. If P(A ∪B) = P(A n B) for any two events A and B, then
(a) P(A) = P(B) (b) P (A) > P (B)
(c) P(A ) < P(B) (d) none of these
Sol: (a) We have, P(A ∪ B) = P(A n B)
P(A) + P(B) – P(A ∩ B) = P(A ∩ B)

Q25. If 6 boys and 6 girls sit in a row at random. The probability that all the girls sit together is

Q26. A single letter is selected at random from the word ‘PROBABILITY’. The probability that it is a vowel is

Q27. If the probabilities for A to fail in an examination is 0.2 and that for B is 0.3, then the probability that either A or B fails is

Q29. If M and N are any two events, tlie probability that at least one of them occurs is                            .
(a) P(M) + P(N) – 2 P(M ∩N)         
(b) P(M) + P(N) – P(M ∩ N)
(c) P(M) + P(N) + P(M ∩ N)
(d) P(M) + P(N) + 2P(M∩N)
Sol: (B) If M and N are any two events.
.-. P(M ∪N) = P(M) + P(N) – P(M ∩ N) .

True/False Type Questions

Q30. The probability that a person visiting a zoo will see the giraffe is 0.72, the probability that he will see the bears is 0.84 and the probability that he will see both is 0.52.
Sol: False
P(to see giraffe or bear) = P (giraffe) + P (bear) – P(giraffe and bear)

=0.72 + 0.84-0.52= 1.04
which is not possible.

Q31. The probability that a student will pass his examination is 0.73, the probability of the student getting a compartment is 0.13, and the probability that the student will either pass or get compartment is 0.96.
Sol: False
Let A = Student will pass examination
B = Student will getting compartment
P(A) = 0.73, P(B) = 0.13 and P(A or B) = 0.96
P(A or B) = P(A) + P(B) = 0.73 + 0.13 = 0.86
But P(A or B) = 0.96
Hence, given statement is false.

Q32.The probabilities that a typist will make 0, 1,2, 3, 4, 5 or more mistakes in typing a report are, respectively, 0.12, 0.25, 0.36, 0.14, 0.08, 0.11.
Sol: False
Sum of these probabilities must be equal to 1.
P(0) + P( 1) + P( 2) + P(3) + P{ 4) + P(5)
= 0.12 + 0.25+0.36 + 0.14 + 0.08 + 0.11 = 1.06 which is greater than 1,
So, it is false statement.

Q33. If A and B are two candidates seeking admission in an engineering College. The probability that A is selected is .5 and the probability that both A and B are selected is at most .3. Is it possible that the probability of B getting selected is 0.7?

Sol. False
Given that, P(A ) = 0.5, P(A ∩B)< 0.3
Now, P(A) x P(B) ≤ 0.3
=>0.5 x P(B) ≤0.3
=> P(B) ≤0.6
Hence, it is false statement

Q34. The probability of intersection of two events A and B is always less than or equal to those favourable to the event
Sol: True
We know that A ∩ B ⊂ A
P(A ∩ B) ≤ P(A)
Hence, it is a true statement.

Q35. The probability of an occurrence of event A is .7 and that of the occurrence of event B is .3 and the probability of occurrence of both is .4.
Sol: False
A ∩B⊆ A, B
P(A ∩B) ≤ P(A), P(B)
But given that P(B) = 0.3 and P(A ∩B) = 0.4, which is not possible.

Q36. The sum of probabilities of two students getting distinction in their final examinations is 1.2.
Sol: True
Probability of each student getting distinction in their final examination is less than or equal to 1, sum of the probabilities of two may be 1.2.
Hence, it is true statement.

Fill in the Blanks Type Questions

Q37. The probability that the home team will win an upcoming football game is 0.77, the probability that it will tie the game is 0.08, and the probability that it will lose the game is ______.
Sol: P(losing) = 1 – (0.77 + 0.08) = 0.15

NCERT Exemplar Problems Class 11 Mathematics

The post NCERT Exemplar Problems Class 11 Mathematics Chapter 16 Probability appeared first on Learn CBSE.

Download Formula Book for Class 10 Maths and Sciece

NCERT Solutions For Class 10 Kshitiz II Hindi Chapter 17

More Resources For Class 10

• Solved CBSE Sample papers For Maths
• Video Solutions

The post NCERT Solutions For Class 10 Kshitiz II Hindi Chapter 17 appeared first on Learn CBSE.

Download Formula Book for Class 10 Maths and Science

NCERT Solutions For Class 10 Sanchyan II Hindi Chapter 1

The post NCERT Solutions For Class 10 Sanchyan II Hindi Chapter 1 appeared first on Learn CBSE.

Download Formula Book for Class 10 Maths and Science

NCERT Solutions For Class 10 Sparsh II Hindi Chapter 10

The post NCERT Solutions For Class 10 Sparsh II Hindi Chapter 10 appeared first on Learn CBSE.

Download Formula Book for Class 10 Maths and Science

NCERT Solutions For Class 10 Sparsh II Hindi Chapter 11

The post NCERT Solutions For Class 10 Sparsh II Hindi Chapter 11 appeared first on Learn CBSE.

Download Formula Book for Class 10 Maths and Science

NCERT Solutions For Class 10 Sparsh II Hindi Chapter 12

The post NCERT Solutions For Class 10 Sparsh II Hindi Chapter 12 appeared first on Learn CBSE.

Download Formula Book for Class 10 Maths and Science

NCERT Solutions For Class 10 Sparsh II Hindi Chapter 13

The post NCERT Solutions For Class 10 Sparsh II Hindi Chapter 13 appeared first on Learn CBSE.

Download Formula Book for Class 10 Maths and Science

NCERT Solutions For Class 10 Sparsh II Hindi Chapter 14

The post NCERT Solutions For Class 10 Sparsh II Hindi Chapter 14 appeared first on Learn CBSE.

Download Formula Book for Class 10 Maths and Science

NCERT Solutions For Class 10 Sparsh II Hindi Chapter 15

The post NCERT Solutions For Class 10 Sparsh II Hindi Chapter 15 appeared first on Learn CBSE.

Download Formula Book for Class 10 Maths and Science

NCERT Solutions For Class 10 Sparsh II Hindi Chapter 16

The post NCERT Solutions For Class 10 Sparsh II Hindi Chapter 16 appeared first on Learn CBSE.

Download Formula Book for Class 10 Maths and Science

NCERT Solutions For Class 10 Sparsh II Hindi Chapter 17

The post NCERT Solutions For Class 10 Sparsh II Hindi Chapter 17 appeared first on Learn CBSE.

Metals and Non-Metals Chapter Wise Important Questions Class 10 Science

Important QuestionsNCERT SolutionsSample PapersNCERT Exemplar Solutions

Short Answer Type Questions[l] [2 Marks]-Year 2015

1.Write one example of each of
(i) a metal which is so soft that, it can be cut with knife and a non-metal which is the hardest sustance.
(ii) a metal and a non-metal which exist as liquid at room temperature.
Answer.
(i) Sodium, carbon (diamond).
(ii)Mercury is liquid metal, bromine is liquid non-metal.

2.Mention the names of the metals for the following:
(i) Two metals which are alloyed with iron to make stainless steel.
(ii) Two metals which are used to make jewellary.
Answer.
(i) Nickel and chromium.
(ii) Gold and platinum.

Short Answer Type Questions[ll] [3 Marks]-Year 2015

3.State three reasons for the following facts
(i) Sulphur is a non-metal
(ii)Magnesium is a metal
One of the reasons must be supported with a chemical equation.
Answer.

4.What is cinnabar? How is metal extracted from cinnabar? Explain briefly.
Answer. Cinnabar is HgS.
Mercury is obtained by roasting cinnabar. HgO formed is thermally unstable and gives mercury.

Mercury can be purified by distillation.

5.(a) Write the electron dot structures for potassium and chlorine.
(b) Show the formation of KCl by the transfer of electrons.
(c) Name the ions present in the compound, KCl.
Answer.

6.(a)State the electron-dot structure for calcium and sulphur.
(b) Show the formation of CaS by the transfer of electrons.
(c) Name the ions present in this compound CaS. Atomic number of Ca = 20, O = 16.
Answer.

Long Answer Type Question [5 Marks] -Year 2015

7.(a) Write electron dot diagram for chlorine (At No. 17) and calcium (At No. 20).
Show the formation of calcium chloride by transfer of electrons.
(b) Identify the nature of above compound’and explain three physical properties of such compound. Answer.

(b) It is ionic compound.
Physical properties
1.It is hard and solid.
2.It has high melting and boiling point.
3.It soluble in water.

Short Answer Type Questions[ll] [3 Marks] -Year 2014

8. You are given samples of three metals. Sodium, magnesium and copper. Suggest any two activities to arrange them in order of decreasing activity.
Answer. Activity 1: Sodium reacts with cold water vigorously to form sodium hydroxide
and hydrogen gas

Magnesium does not react with cold water but with hot water to form magnesium ! hydroxide and hydrogen gas.

Hence sodium is more reactive than magnesium.

9.You are provided with magnesium ribbon and sulpher powder. Explain with the help of an activity that metal oxides are basic and non-metal oxide are acidic in nature.
Answer.
Aim: To test the nature of oxides formed by metals and non-metals. Materials Required: Sulphur powder, Mg ribbon, water, blue litmus paper, red litmus paper.
Procedure:
1.Take magnesium ribbon with a pair of tongs and
burn it in flame in the presence of air.
2.Collect the product formed and dissolve it in warm water.
3.Add red litmus paper into it.
4.Observe the change in colour and decide the nature of the oxide formed.
5.Burn sulphur in a deflagrating spoon in the presence of air and dissolve the oxide formed in water.
6.Dip blue litmus paper into the solution and observe the changein the colour and decide the nature of the oxide formed.
Observation: The oxide formed by metal turns red litmus blue whereas oxide of non-metal turns blue litmus red.

Conclusion: Most of the metallic oxides are basic in nature whereas most of the non-metallic oxides are acidic in nature.

Long Answer Type Question [5 Marks] -Year 2014

10.(a) An ore on treatment with dilute hydrochloric acid produces brisk effervesces. What type of ore is this? What steps will be required to obtain metal from the enriched ore. ,
(b) Copper coin is kept immersed in silver nitrate solution for some time. What change will take place in coin and colour of the solution ? Write balanced chemical equation of the reaction involved.
Answer.
(a) Carbonate ore:
(i) Calcination: Carbonate ore is heated in limited supply of air and oxide is obtained, e.g.

(b) Copper, being more reactive than silver will displace silver from silver nitrate solution and there will be deposition of silver on copper coin. The colour of solution will turn to blue.

Short Answer Type Question[l] [2 Marks] -Year 2013

11.Give reason for the following:
(a) School bells are made up of metals.
(b) Electric wires are made up of copper.
Answer.
(a) It is because metals are sonorous, i.e. they produce sound when struk with a hard substance.
(b) It-is because copper is good conductor of electricity.

Short Answer Type Question[ll] [3 Marks] -Year 2013

12. Suggest a method of reduction for the following metals during their metallurgical processes:
(i) metal ‘A’ which is one of the last, second or third position in the reactivity.
(ii) metal ‘B’ which gives vigorous reaction even with water and air.
(iii) metal ‘C’ which is kept in the middle df activity series.
Answer.
(i) ‘A’ can be obtained by chemical reduction using carbon or carbon monoxide as reducing agent.
(ii) ‘B’ can be obtained by electrolytic reduction.
(iii) ‘C’ can be reduced by reducing agent like ‘Al’.

Long Answer Type Question [5 Marks] -Year 2013

13.(a) Define activity series of metals. Arrange the metals gold, copper, iron and magnesium in order of their increase in reactivity.
(b) What will you observe when:
(i) Some zinc pieces are put in copper sulphate solution.
(ii) Some silver pieces are put into green coloured ferrous sulphate solution.
Answer.
(a) The series of metals in which metals are arranged in decreasing order of their reactivity.
Au < Cu < Fe < Mg is increasing order of reactivity.
(b) (i) The blue solution will become colourless and reddish brown copper metal will be deposited.

Reaction will not take place because Ag’ is less reactive than iron.

Very Short Answer Type Question [1 Mark] -Year 2012

14.A green layer is gradually formed on a copper plate left exposed to air for a week in a bathroom. What could this green substance be?
Answer. It is due to the formation of basic copper carbonate [CuC0₃.Cu(0H)₂].

Short Answer Type Questions[l] [2 Marks] -Year 2012

15.Name the following:
(a) A metal, which is preserved in kerosene.
(b) A lustrous coloured non-metal.
(c) A metal, which can melt while kept on palm.
(d) A metal, which is a poor conductor of heat.
Answer.
(a) Sodium is preserved in kerosene.
(b) Iodine is lustrous coloured non-metal.
(c) Gallium. ‘
(d) Lead.

16. Explain why calcium metal after reacting with water starts floating on its * surface. Write the chemical equation for the reaction. Name one more metal
that starts floating after some time when immersed in water.
Answer. Calcium starts floating because the bubbles of hydrogen gas formed stick to the
surface of metal.

Magnesium reacts with hot water and starts floating due to the bubbles of hydrogen gas sticking to its surface.

17. Give reason for the following:
(a) Aluminium oxide is considered as an amphoteric oxide.
(b) Ionic compounds conduct electricity in molten state.
Answer.
(a) It is because it reacts with acids as well as bases to produce salts and water.’Al’ is less electropositive metal. So, it forms amphoteric oxide which can react with acid as well as base.
(b) Ionic compounds can conduct electricity in molten state because ions ’ become free to move in molten state.

Short Answer Type Questions[ll] [3 Marks] -Year 2012

18.(a) Explain the formation of ionic compound CaO with electron dot structure. Atomic number of calcium and oxygen are 20 and 8 respectively.
(b) Name the constituent metals of bronze.
Answer.

(b) Bronze is made up of copper and tin.

19. A metal ‘X’ acquires a green colour coating on its surface on exposure to air.
(i) Identify the metal ‘X’ and name the process responsible for this change.
(ii)Name and write chemical formula of the green coating formed on the metal.
(iii) List two important methods to prevent the process.
Answer.
(i) Metal is copper. The process is corrosion.
(ii)Basic copper carbonate [CuCO₃.Cu(0H)₂].
(iii)
• It should be coated with tin
• It should be mixed with other metals to form alloys.

20.Write balanced equations for the reaction of:
(i) aluminium when heated in air. Write the name of the product.
(ii) iron with steam. Name the product obtained.
(iii) calcium with water. Why does calcium start floating in water?
Answer.

The bubbles of hydrogen stick to the surface of metal that is why it floats.

21.Write balanced chemical equations for the following reactions:
(a) Dilute sulphuric acid reacts with aluminium powder.
(b) Dilute hydrochloric acid reacts with sodium carbonate.
(c) Carbon dioxide is passed through lime water.
Answer.

22. What is meant by ‘rusting’? With labelled diagrams, describe an activity to find out the conditions under which iron rusts.
Answer. The process in which iron reacts with oxygen in the presence of moisture to form reddish brown coating of hydrated ferric oxide [Iron (III) oxide].Fe2O₃ xH₂0
Activity:
(i) Take three boiling tubes A, B and C.
(ii) Pour some water in test tube A Put iron nails in it and cork it.
(iii) Pour boiled distilled water in another test tube B and put iron nails in it. Add 1 ml of ojl over it such that oil flo’ats over it and prevents the air from entering.
(iv) Take some iron nails in test tube C and put some anhydrous calcium chloride in it and cork it.
(v) Leave all the three test tubes for one day and then observe.

Observation: Iron nails get rusted in test tube A because both air and water are present in it. Iron nails do not get rusted in B because there is water but no air. In C, rusting will not take place because there is neither air nor water. Conclusion: Iron gets rusted in the presence of air and water.

23.(a) Show the formation of Na₂O by the transfer of electrons between the combining atoms.
(b) Why are ionic compounds usually hard?
(c) How is it that ionic compounds in the solid state do not conduct electricity but they do so when in molten state?
Answer.

(b) It is due to strong force of attraction between oppositely charged ions.
(c) In solid state, ions are not free to move whereas in molten state ions are free to move, therefore, they conduct electricity in molten state.

24. (a) Show on a diagram the transfer of electrons between the atoms in the formation of MgO. Write symbols of cation and anion present in MgO.
(b) Name the solvent in which ionic compounds are generally soluble.
(c) Why are aqueous solutions of ionic compounds able to conduct electricity?
Answer.

(b) Ionic compounds are soluble in water.
(c) It is because aqueous solutions consist of ions which can move freely in them and carry current.

25.What are amphoteric oxides? Choose the amphoteric oxides from amongst the following oxides:
Na₂O, ZnO, Al₂O₃, CO₂, H₂O
Answer.Those oxides which reacts with acids as well as bases to produce salts and water are called amphoteric oxides, e.g. Na₂O, ZnO, are amphoteric oxides among given oxides.

26.Define the terms:
(i) mineral
(ii) ore, and
(iii) gangue.
Answer.
(i) Mineral: It is a naturally occurring substance from which metal may or may not be extracted profitably or economically, e.g. A1 cannot be extracted profitably from mica.
(ii)Ore: It is a rocky material which contains sufficient quantity of mineral so that metal can be extracted profitably, e.g. zinc blende is an ore of zinc from which zinc can be extracted profitably.
(iii) Gangue: It is a rocky material which is present along with the mineral in the ore, e.g. FeO is gangue in extraction of copper.

Long Answer Type Questions [5 Marks] -Year 2012

27. (a) Write the chemical name of the coating that forms on silver and copper articles when these are left exposed to moist air.
(b) Explain what is galvanisation. What purpose is served by it?
(c) Define an alloy. How are alloys prepared? How do the properties of iron change when:
(i) small quantity of carbon,
(ii) nickel and chromium are mixed with it.
Answer.
(a) Ag₂S (silver sulphide) is formed on silver, basic copper carbonate CuCO₃. CU(OH)₂ is formed on copper.
(b) The process of coating zinc over iron is called galvanisation. It is used to prevent rusting of iron.
(c) Alloy is a homogeneous mixture of two or more metals. One of them can be non-metal. Alloys are prepared by melting two or more metals together.
(?) Iron does not rust on adding small,quantity of carbon.
(ii) When we form alloy of iron with nickel and chromium, we get stainless steel which is malleable and does not get rusted.

28.(a) Differentiate between roasting and calcination. Explain the two with the help of suitable chemical equations. How is zinc extracted from its ore?
(b) Name two metals that can be used to reduce metal oxides to metals.
Answer.
(a) Roasting: It is a process in which sulphide ore is heated in the presence of oxygen to convert into oxide.

Cali ination: It is a process in which carbonate ore is heated in the absence of air to form oxide.

By reduction process, Zn can be extracted from its ore.

(b) Aluminium, Magnesium.

29. (a) In the formation of compound between two atoms A and B, A loses two electrons and B gains one electron.
(i) What is the nature of bond between A and B?
(ii) Suggest the formula of the compound formed between A and B.
(b) On similar lines explain the formation of MgCl₂ molecule.
(c) Common salt conducts electricity only in the molten state. Why?
(d) Why is melting point of NaCl high?
Answer.

30.(a) Carbon cannot be used as reducing agent to obtain Mg from MgO. Why?
(b) How is sodium obtained from molten sodium chloride? Give equation of the reactions.
(c) How is copper obtained from its sulphide ore? Give equations of the reactions.
Answer.
(a) It is because ‘Mg’ is stronger reducing agent than carbon.
(b) Sodium is obtained from molten NaCl by electrolysis.

Blister Copper is purified by electrolytic refining.

31.How is the method of extraction of metals high up in the reactivity series different from that for metals in the middle ? Why the same process cannot be applied for them? Explain giving equations, the extraction of sodium.
Answer. Metals high up in the series are obtained by electrolytic reduction because these metals are strong reducing agents and therefore, cannot be obtained by chemical reduction.
Metals in middle of series are less reactive and can be obtained by chemical reduction. The same process can not be used for both of them as highly reactive metals can not be obtained by chemical reduction.
Extraction of sodium is done by electrolysis of molten sodium chloride.

32.Write the names and symbols of two most reactive metals. Explain by drawing electronic structure how any one of the two metals react with a halogen. State any four physical properties of the compound formed.
Answer. K(Potassium) and Na(Sodium) are the two most reactive metals. K’ and Na‘ are electronic structures as they have one valence electron.


where ‘F’ is a halogen.
Four physical properties of the compounds formed by these elements and
halogens are:
(i) They have high melting point.
(ii)They are soluble in water.
(iii) They conduct electricity in molten state not in solid state.
(iv) They are solid and somewhat hard.

33.A metal ‘M’ which is one of the best conductor of heat and electricity used in making electric wires is found in nature as sulphide ore M2S?
(i) Name the metal ‘M’
(ii) Which process will be suitable for extraction of this metal M from its ore M2S? Write the balanced chemical reactions involved in the process of ‘ extraction.
(iii) With the help of a labelled diagram, explain the process of electrolytic refining of the metal.
Answer.
(i) Copper

(ii) It is concentrated by froth-floatation process.
Impure copper is purified by electrolytic refining.
(iii) Impure metal is taken as anode whereas pure metal is taken as cathode.iSoluble salt of metal is taken as electrolyte. When electric current is ipassed, impure metal changes to ions which gain electrons at cathode
iand change into pure metal. Impurities are left behind as anode mud.

34.Give reasons for the following:
(i) Silver and copper lose their shine when they are exposed to air. Name the substance formed on their surface in each case.
(ii) Tarnished copper vessels are cleaned with tamarind juice.
(iii) Aluminium is more reactive than iron yet there is less corrosion of aluminium as compared to iron when both are exposed to air.
Answer.
(i) These metals get corroded. Silver forms black Ag2S (silver sulphide) and copper form greenish layer of basic copper carbonate CuCO₃. CU(OH)₂ .
(ii) Tamarind contains acid which reacts with basic copper carbonate and product gets dissolved and removed from copper vessel.
(in) Aluminium forms oxide layer on its surface which does not further react with air.

35.(a) Write the electron dot structures of sodium, oxygen and magnesium.
(b) Show the formation of Na₂O and MgO by transfer of electrons. Name the ions present in these compound.
(c) List three properties of ionic compounds.
Answer.

(i) They are solids having high melting point.
(ii) They are soluble in water.
(iii) They conduct electricity in molten state as well as in aqueous solution.

36. What are alloys? How are they made? Name the constituents and uses of brass, bronze and solder.
Answer. Alloys are homogeneous mixtures of two or more metals. One of them can be a non-metal also. They are made by melting a metal which is in large amount first and then adding the other metal. ,
Brass contains copper and zinc. It is used for making decorative articles. Bronze contains copper and tin. It is used for making statues and medals. Solder contains lead and tin. It is used for soldering purposes.

37. A metal (E) is stored under kerosene. When a small piece of it is left open in the air, it catches fire. When the product formed is dissolved in water, it turns red litmus to blue.
(i) Name the metal (E).
(ii)Write the chemical equation for the reaction when it is exposed to air and when the product is dissolved in water.
(iii) Explain the process by which the metal is obtained from its molten chloride.
Answer.
(i) ‘E’ is sodium which catches fire in presence of moisture.

(iii) Electrolytic reduction: Electric current is passed through molten NaCl. Sodium is formed at cathode and chlorine gas is liberated at anode.

38. Write two differences between calcination and roasting.
Answer.

Very Short Answer Type Questions [1 Mark] -Year 2011

39. A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y and Z.
Answer. ‘X’ is carbon, ‘Y’ is diamond as it is the hardest natural substance and ‘Z’ is graphite as it is good conductor of electricity.

40. Why does calcium float in water?
Answer. It is because hydrogen gas is formed which sticks to surface of calcium, therefore it floats. –

41.Name a non-metal which is lustrous and a metal which is non-lustrous. Iodine is a non-metal which is lustrous,
Answer.lead is a non-lustrous metal.

42.Which gas is liberated when a metal reacts with an acid? How will you test the presence of this gas?
Answer. Hydrogen gas is formed. Bring a burning matchstick near to it, H2 will burn explosively with ‘pop’ sound.

43.Name the metal which reacts with a very dilute HNOs to evolve hydrogen gas.
Answer. Magnesium

44.Name two metals which are found in nature in the free state.
Answer.(i) Gold (ii) Silver

Answer Type Questions[l] [2 Marks] -Year 2011

45.The way, metals like sodium, magnesium and iron react with air and water is an indication of their relative positions in the ‘reactivity series’. Is this statement true ? Justify your answer with examples.
Answer.Yes, sodium reacts explosively even with cold water, it is most reactive. Magnesium reacts with hot water, it is less reactive than Na. Iron reacts only with steam which shows it is least reactive among the three.

46. X + YSO₄——-> XSO₄+ Y
Y + XSO₄ ——–> No reaction
Out of the two elements, ‘X’ and ‘Y’, which is more reactive and why?
Answer. ‘X’ is more reactive than ‘Y’ because it displaces ‘Y’ from its salt solution.

47.What is an alloy? State the constituents of solder. Which property of solder makes it suitable for welding electrical wires?
Answer. Alloy is a homogeneous mixture of two or more metals. One of them can be a non-metal also. Solder consists of lead and tin. It has low melting point which makes it suitable for welding electrical wires.

48.Using the electronic configurations, explain how magnesium atom combines
with oxygen atom to form magnesium oxide by transfer of electrons.
Answer.

49.When a metal X is treated with cold water, it gives a base Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z.
Answer.

50. Write chemical equations that shows aluminium oxide reacts with acid as well as base.
Answer.

Long Answer Type Questions [5 Marks] -Year 2011

51.(a) Name the main ore of mercury. How is mercury obtained from its ore? Give balanced chemical equation.
(b) What is thermite reaction? How is it used to join the railway tracks or cracked machine parts?
(c) Name the method used to extract metals of high reactivity.
Answer.
(a) Cinnabar
Mercury is obtained from its ore by roasting.

(b) When aluminium is heated with Fe203 to get molten iron, it is called thermite reaction.

Molten iron is used to weld broken railway tracks.
(c) Electrolytic reduction

52.(a) How can the metals at the top of the reactivity series be extracted from their ores? Explain with an example.
(b) Name any one alloy made from
(i) a metal and a non-metal, and
(ii) two metals.
Answer.
(a) These metals are extracted by electrolytic reduction, e.g. aluminium is obtained from bauxite by electrolytic reduction.
(b) (i) Steel is made up of iron and carbon.
(ii) Brass is made up of copper and zinc.

53.(a) Give two methods to prevent the rusting of iron.
(b) Name the ores of the following metals:
(i) mercury, and
(ii) zinc
(c) Explain with the help of a diagram, how copper metal can be refined? Label the important arrangements in the experimental set up.
Answer.
(a)(i) Painting (ii) Galvanisation
(b)(i) Cinnabar (ii) Zinc Blende

(c) Impure copper is taken as anode whereas pure copper is taken as cathode. Copper sulphate solution (CuS04) is taken as electrolyte. When electric current is passed, impure copper changes to ions which gain electrons at cathode and change into pure copper. Impurities are left behind as anode mud.
At anode:
At Cathode:

54.With the help of a suitable example, explain how ionic compounds are formed. State any three general properties of ionic compounds.
Answer.Ionic compounds are formed by transfer of electrons from metal to non-metals, e.g.

General Properties:
(i) They are the solids having high melting point.
(ii) They are soluble in water.
(iii) They conduct electricity in molten state as well as in aqueous solution.

55.(a) Explain with an example how the metal (X) which is low in reactivity series and metal (Y) which is high in the reactivity series are obtained from their compounds by reduction process.
(b) Write the electronic configurations of sodium and chlorine. Show the formation of sodium chloride from sodium and chlorine by the transfer of electrons.
(c) List any two observations when a highly reactive metal is dropped in water.
Answer.
(a) ‘X’ is obtained by chemical reduction.
‘Y’ is obtained by electrolytic reduction.

(c) (i) Metal will catch fire.
(ii) Alkali solution is formed which turns red litmus blue.

56.(a) The reaction of metal (X) with ferric oxide is highly exothermic. Metal
(X) is obtained from its oxides by electrolytic reduction. Identify (X) and write its reaction with ferric oxide.
(b) Give reason to justify that aluminium oxide is an amphoteric oxide. Also, give another example of amphoteric oxide.
(c) Mention constituent metals present in bronze.
Answer. (a) ‘X’ is ‘Al’

(b) AI₂O₃ reacts with acid as well as base therefore it is amphoteric oxide.

Zinc oxide is also an amphoteric oxide.
(c) Bronze contains’ copper and tin.

Very Short Answer Type Questions [1 Mark] -Year 2010

57.What is the valency of silicon with atomic number 14?
Answer. Its valency is equal to 4.

58.What is the valency of phosphorus with atomic number 15?
Answer. Phosphorus has valency 3.

59.What is the valency of an element with atomic number 35?
Answer. Its valency is 1.

Short Answer Type Question[I] [2 Marks] -Year 2010

60.Elements magnesium and oxygen respectively belong to group 2 and group 16 of the Modern Periodic Table. If the atomic numbers of magnesium and oxygen are 12 and 8 respectively, draw their electronic configurations and show the process of formation of their compound by transfer of electrons.
Answer.(Mg)=2,8,2

Long Answer Type Question [5 Marks] -Year 2010

61.No reaction takes place when granules of a solid ‘A’ are mixed with a powder of solid ‘B\ However when the mixture is heated, a reaction starts with evolution of much heat. Product ‘C’ of the reaction settles down as a liquid metal and solid product ‘D’ keeps floating over the liquid ‘C\ This reaction is sometimes used for making metals for ready use in odd places.
(i) Based on this information, make assumptions about ‘A’ and ‘B’ and corresponding deductions about ‘C’ and ‘D’ and write a balanced chemical equation for the reaction. Include in the chemical equation about physical states of the reactants and products, need of heating for starting the reaction and the reaction being exothermic.
(ii) Name two types of chemical reactions to which this reaction can belong.
Answer.
(i) ‘A’ is aluminum, ‘B’ is ferric oxide [Iron(III) oxide],

(ii)This reaction is displacement reaction because AT is displacing ‘Fe’. It is also a redox reaction because AT is reducing agent and Fe2O₃is oxidising agent.

Very Short Answer Type Question [1 Mark] -Year 2009

62. Arrange the following metals in the decreasing order of reactivity: Na, K, Cu, Ag.
Answer. K > Na > Cu > Ag

Short Answer Type Questions[ll] [3 Marks] -Year 2009

63. An ore on heating in air produces sulphur dioxide. Which process would you suggest for its concentration? Describe briefly any two steps involved in the conversion of this concentrated ore into related metal.
Answer. It is concentrated by froth-floatation process.
(i) Roasting: The concentrated sulphide ore is heated strongly in the presence of oxygen to convert it into its oxide.

(ii)Reduction : This oxide of metal is reduced with suitable reducing agent to get free metal.

64. Give reasons for the following observations:
(i) Ionic compounds in general have high melting and boiling points.
(ii) Highly reactive metals cannot be obtained from their oxides by heating
them with carbon.
(iii) Copper vessels get a green coat when left exposed to air in the rainy season.
Answer. (i) Ionic compounds have high melting and boiling points due to strong force of attraction between oppositely charged ions.
(ii) It is because these metals themselves are strong reducing agents. Therefore, cannot be reduced by reducing agent like carbon.
(iii) Copper vessels react with CO₂, O₂ and moisture to form green-coloured basic copper carbonate
[CuCO₃.Cu(OH)₂].

65. State reasons for the following observations:
(i) The shining surface of some metals becomes dull when exposed to air for a long time.
(ii) Zinc fails to evolve hydrogen gas on reacting with dilute nitric acid.
(iii) Metal sulphides occur mainly in rocks but metal halides occur mostly in sea and lake waters.
Answer.
(i) It is because metal reacts with substances present in atmosphere to form surface compounds which make it dull.
(ii) It is because dil. HNOs is an oxidising agent therefore zinc gives NO and notH₂ with dil. HNOs.
(iii) It is because sea water contains sodium chloride due to which metal halides are formed, whereas sulphur is found below rocks. Therefore, metal – sulphides are formed in rocks.

66. State reasons for the following:
(i) Electric wires are covered with rubber like material.
(ii)From dilute hydrochloric acid, zinc can liberate hydrogen gas but copper cannot.
(iii) Sulphide ore of a metal is first converted to its oxide to extract the metal from it.
Answer.
(i) It is because rubber is an insulator and does not allow current to flow through it.
(ii) Zinc is more reactive than hydrogen. Therefore, it can displace hydrogen from dilute HCl whereas copper cannot, because it is less reactive than hydrogen. ,
(iii) It is because it is easier to reduce oxide ore as compared to sulphide ore.

Long Answer Type Questions [5 Marks] -Year 2009

67.(a) What is meant by corrosion? Name any two methods used for the prevention
of corrosion.
(b) Suppose you have to extract metal M from its enriched sulphide ore. If M is in the middle of the reactivity series, write various steps used in extracting this metal.
Answer. (a) Corrosion is a process in which metal reacts with substances present in the environment to form surface compounds.
Prevention:
(i) Galvanisation is a process to prevent corrosion of iron.
(ii)Electroplating is also used to prevent corrosion.
(b)(i) Concentration of ores: Sulphide ore will be concentrated by froth- floatation process. Sulphide ore will be collected in froth whereas gangue will be left behind.
(ii) Roasslng: Sulphide ore is heated strongly in the presence of O₂ to form metal oxide and sulphur dioxide.
2MS + 3O₂ ————- ► 2MO + 2SO₂
(iii) Reduction: MO reacts with carbon (acts as reducing agent) to form metal and CO.
MO + C —-> M + CO
(iv) Electrolytic refining: Impure metal ‘M’ is purified by electrolytic refining. Impure metal is taken as anode, pure metal is taken as cathode, soluble salt of metal is taken as electrolyte. Impure metal forms metal ions which gain electrons and form pure metal at cathode.

68.(a) Distinguish between ionic and covalent compounds under the following properties:
(i) Strength of forces between constituent elements.
(ii) Solubility of compounds in water.
(iii) Electrical conduction in substances.
(b) Explain how the following metals are obtained from their compounds by the reduction process:
(i) Metal M which is in the middle of the reactivity series.
(ii) Metal N which is high up in the reactivity series.
Give one example of each type.
Answer.

(b) (i) Metal M which is in the middle of the reactivity series is reduced by aluminium, e.g.
3MnO₂(s) + 4Al(s) ——–> 2Al_2O3(s) + 3Mn(l)
(ii) Metal N will be obtained by electrolytic reduction, e.g. A1 is obtained by electrolytic reduction.

Download Formula BookPhysics eBookChemistry eBookBiology eBook

The post Metals and Non-Metals Chapter Wise Important Questions Class 10 Science appeared first on Learn CBSE.

Download Formula BookPhysics eBookChemistry eBookBiology eBook

Life  Processes Chapter Wise Important Questions Class 10 Science

Short Answer Type Questions[l] [2 Marks] -Year 2015

1.What are enzymes? Name any one enzyme of our digestive system and write its function.
Answer. Enzymes are biological catalysts. Catalysts are proteins that increase the rate of chemical reactions
without being used up. For example: Amylase catalyses the breakdown of starch into sugars in the mouth and small intestine

2.(i) Write the balanced chemical equation for the process of photosynthesis,
(ii) When do the desert plants take up carbon dioxide and perform photosynthesis ?
Answer.
(i) Photosynthesis can be represented using a chemical equation. The overall balanced equation is

(ii) Desert plants open up their stomata during night and take in CO₂. Stomata remains close during the day time to prevent the loss of water by i transpiration. They store the CO₂ in their cells until the sun comes out and they can carry on with photosynthesis during the day time.

Short Answer Type Questions[ll] [3 Marks] -Year 2015

3.In single celled organisms diffusion is sufficient to meet all their requirements of food, exchange of gases or removal of wastes but it is not in case of multicellular organisms. Explain the reason for this difference.
Answer. Unicellular organisms can absorb sufficient oxygen because of its complete contact with the atmosphere, but in multicellular organisms the rate of absorption and diffusion becomes very less because all cells are not in direct contact with the atmosphere. Multicellular organisms require greater amount of oxygen to sustain life processes which cannot be fulfilled by the process of diffusion.

4. Draw a diagram of human excretory system and label kidneys, ureters on it.
Answer.

5.Name the acid presents in the following:
(i) Tomato (ii) Vinegar (iii) Tamarind
Answer.
(i) Oxalic acid (ii) citric acid (iii) Tartaric acid.

6.State the role of the following in human digestive system :
(i) Digestive enzymes (ii) Hydrochloric acid (iii) Villi
Answer.
(i) Digestive enzymes – Foods need to be broken into their small or simpler
molecules so that they can be absorbed into the bloodstream. However, the physical breakdown of food is not enough. Enzymes are hence needed for the chemical breakdown of food and speeding up the digestive process. The products of digestion can hence be small enough to be absorbed.
(ii) Hydrochloric acid – Hydro chloric acid helps to kill the germs which might have entered in to the system through food. It creates acidic medium for the pepsin to act on food to breakdown proteins.
(iii) Villi – Villi are finger like projections in the small intestine. They help to increase the surface area for absorption of the digested food. Villi are richly supplied with blood vessel which help to absorb digested food in to the blood stream.

Long Answer Type Question [5 Marks] -Year 2015

7.(a)Explain how does the exchange of gases occur in plants across the surface of stems, roots and leaves.
(b) How are water and minerals transported in plants ?
Answer.
(a) In plants there are tiny pores called stomata on leaves and lenticels in stem which facilitate the exchange of gases. Carbon dioxide is taken in and oxygen given out {during photosynthesis} and vice versa during respiration.
(b) Water and minerals are transported within the plant by the Xylem vessels (mainly in an upward direction); these are part of the vascular system which also includes Phloem vessels.
Phloem transports the products of photosynthesis within the plant, to all parts like the stem, roots, fruits etc. in all directions.

Very Short Answer Type Question [1 Mark] -Year 2014

8. Mention the raw materials required for photosynthesis.
Answer. The following raw materials are required for photosynthesis:
(i) Carbon Dioxide: Plants get CO₂ from atmosphere through stomata.
(ii)Water: Plants absorb water from soil through roots and transport to leaves.
(iii) Sunlight: Sunlight, which is absorbed by the chlorophyll and other green parts of the plant.

Short Answer Type Questions[l] [2 Marks] -Year 2014

9. Why do herbivores have longer, small intestine than carnivores ?
Answer.Digestion of cellulose takes a longer time. Hence, herbivores eating grass need a longer small intestine to allow complete digestion of cellulose. Carnivorous animals cannot digest cellulose due to the absence of enzyme CELLULASE, hence they have a shorter intestine.

10.Write correct sequence of four steps of method for the preparation of temporary mount of a stained leaf peel.
Answer.

1. Take a healthy leaf from the potted plant.
2. Remove a part of the peel from the lower surface of the leaf. You can do this by folding the leaf over and gently pulling the peel apart using forceps. Keeps the peel in a watch glass containing water.
3. Put a few drops of safranin stain in a watch glass.
4. After 2-3 minutes take out the peel and place it on a clean glass slide.
5. Put a drop of glycerin over the peel and place a clean covers lip gently over it with the help of a needle.
6. Remove the excess stain and glycerin with the help of blotting paper.
7.  Observe the slide under magnifications of the compound microscope.

Short Answer Type Questions[ll] [3 Marks] -Year 2014

11.In mammals and birds why is it necessary to separate oxygenated and de-oxygenated blood ?
Answer. Mammals and birds are warm blooded animals. This means they can control their body temperature and do not have to depend on environment for their body temperature regulation. Because of this birds and mammals require optimum oxidization of glucose which would be possible with good supply of oxygen. So it is required to have separate oxygenated and de-oxygenated blood to supply the required amount of oxygen.

12.Draw a neat diagram of excretory system of human beings and label on it:
(i) Left kidney (ii) Urinary bladder
Answer.

13. Draw a diagram of human respiratory system and label on it :
(i) Diaphragm (ii) Larynx
Answer.

14.(a) Name the site of exchange of material between the blood and surrounding cells. (b) Draw a schematic representation of transport and exchange of oxygen and carbon dioxide in human body.
Answer.
(a) Capillaries
(b)

Very Short Answer Type Question [1 Mark] -Year 2013

15.What would be the consequences of deficiency of hemoglobin in your body?
Answer.The deficiency of hemoglobin in our body is called anemia. In anemia, the blood is unable to carry the sufficient amount of oxygen required by the body. So, respiration would be less and less energy will be available to the body. The hemoglobin deficient person will feel weak, pale, lethargic and will be
unable to perform heavy physical work.

Short Answer Type Questions[ll] [3 Marks] -Year 2013

16. List three characteristics of lungs which make it an efficient respiratory surface.
Answer. These features which particularly make our lungs efficient for gas exchange.
1.Thin: the air sac walls are very thin so that gases can quickly diffuse through them. Oxygen is absorbed in to the blood and carbon dioxide is given out in to the lungs to be exhaled out.
2.Moist: the air sacs are moist with mucus so that gases can dissolve before diffusing.
3.Large surface area: the surface area for gases to diffuse through in human lungs is roughly the same as a tennis court. The alveoli help to increase the surface area for absorption of oxygen.
4.Good blood supply: the air sacs or the alveoli have a large capillary network so that large volumes of gases can be exchanged. More the flow of blood more exchange.

17.(a) What is the role of HCl in our stomach ?
(b) What is emulsification of fats ?
(c) Which protein digesting enzyme is present in pancreatic juice ?
Answer.
(a)(i) It sterilises food by killing pathogens and other microbes.
(ii) It has a pH of 2, which is perfect for entyaus such as pepsin to break down proteins as effectively as possible.
(iii) Helps emulsify food (digestion of protein and stimulates the pancreas to produce digestive enzymes and bile) and protects against harmful ‘ bacteria
(b) Breakdown of large gloubule fats into smaller fats droplets is known as emulsification.
(c) Trypsin is the enzyme secreted by the pancreas which aids in digestion of proteins.

18. List in tabular form three differences between arteries and veins.
Answer.

long Answer Type Questions [5 Marks] -Year 2013

19. Draw a diagram of human excretory system and label renal artery and urethra.
State in brief the function of :

1. renal artery
2.  kidney
3.  ureter
4. urinary bladder

Answer.

1. Renal artery: The renal artery carries blood to the kidneys from the abdominal aorta. This blood comes directly from the heart and is sent to the-kidneys to be filtered before it passes through the rest of the body. Up to one-third of the total cardiac output per heartbeat is sent to the renal arteries to be filtered by the kidneys. Each kidney has one renal artery that supplies it with blood. The filtered blood then can exit the renal vein.
2. Kidney: The kidneys perform the essential function of removing waste products from the blood and regulating the water fluid levels. The kidneys regulate the body’s fluid volume, mineral composition and acidity by excreting and reabsorbing water and inorganic electrolytes.
3. Ureter: The ureter is a tube that carries urine from the kidney to the urinary bladder.’ There are two ureters, one attached to each kidney.
4. Urinary bladder: The urinary bladder is an expandable muscular sac that stores urine before it is excreted out of the body through the urethra.

20.(a) Draw a diagram of excretory system in human beings and label the following parts. Aorta, kidney, urinary bladder and urethra.
(b) How is urine produced and eliminated ?
Answer.(a)

(b) Blood from the heart comes into the kidneys afferent and efferent arteriols from the renal arteries where it enters about 2-3 million nephrons per kidney. Then, it goes through the glomerulus a tugt or bunch of blood capillaries and get rid of some of the unwanted substances like urea, uric acid, creatinine in the blood and then continues through the renal tubules. The loop of Henley, reabsorb certain substances such as water (actually if body is dehydrated, body will send anti-diuretic hormone (ADH) to kidneys to prevent extra water from going into urine and thus saving water for body and get rid of anything else that isn’t wanted, then the urine goes through ureters to bladder and then to urethra where it is excreted out of body as urine.

Short Answer Question [I] [2 Marks] -Year 2012

21. Why do the walls of the trachea not collapse’when there is less air in it?
Answer. Rings of cartilages are present in trachea. These rings support the trachea and do not allow the trachea to collapse when there is less air in it.

Short Answer Type Questions [ll] [3 Marks] -Year 2012

22. In human alimentary canal, name the site of complete digestion of various components of food. Explain the process of digestion.
Answer.In small intestine, complete digestion of various components of food take place. The process of digestion of food in mouth, stomach and small intestine in human
body are as follows:
Mouth: Digestion of food begins in the mouth. Saliva present in mouth contains a digestive enzyme, called salivary amylase, maltose and dextrins, which breaks down starch into sugar.
Stomach: Stomach stores and mixes the food received from the oesophagus with gastric juices. The main components of gastric juice are hydrochloric acid, mucus and pepsinogen. Hydrochloric acid dissolves bits of food and creates an acidic medium. In this medium, pepsinogen is converted to pepsin which is a protein-digesting enzyme. Mucus protects the inner lining of the stomach from the action of HC1.
Small Intestine: Small intestine is the site of complete digestion of carbohydrates, proteins and fats. Small intestine produces intestinal juice from the glands present in its wall. The intestinal juice helps in further digestion of food. Small intestine also obtains digestive juices from liver and pancreas. The liver produces bile juice that causes emulsification of fats and the pancreas produces pancreatic juice for digesting proteins and emulsified fats. This digested food is finally absorbed through the intestinal walls.

23. List the three kinds of blood vessels of human circulatory system and write ¦ their functions in tabular form.
Answer. Three types of blood vessels in human circulatory system are: Arteries, Veins and Capillaries.
Their functions are tabulated below:

Lonq Answer Type Questions [5 Marks] -Year 2012

24.(a) Draw a diagram to show open stomatal pore and label on it:
(i) guard cells
(ii) chloroplast
(b) State two functions of stomata.
(c) How do guard cells regulate the opening and closing of stomatal pore?
Answer.(a)

(b) Two functions of stomata are:
(i) Exchange of gases between the plant and the atmosphere takes place through stomata.
(ii)Transpiration in plants takes place through stomata.
(c) Opening and Closing of Stomatal Pore: The opening and closing of the pore is a function of the guard cells. The guard cells swell when water flows into them causing the stomatal pore to open. Similarly, the pore closes if the guard cells shrink. As large amount of water is lost through these stomata, the plant closes these pores when it does not require carbon dioxide for photosynthesis.

25.(a) Draw a diagram of human respiratory system and label the following:
(i) part where air is filtered by fine hair and mucus
(ii) part which terminates in balloon – like structures
(iii) balloon – like structures where exchange of gases takes place. (iv) part which separates chest cavity from abdominal cavity.
(b) Why is the rate of breathing in aquatic organisms much faster than in terrestrial organisms?
Answer.(a)

(b) Quantity of dissolved oxygen is fairly low in water as compared to the amount of oxygen in air. Aquatic organisms therefore have to breath faster than terrestrial organisms to absorb the required amount of oxygen from the water.

26. Draw a neat diagram of excretory system of human beings and label the following:
(i) Kidney
(ii) Ureter
(iii) Urinary Bladder
(iv) Urethra
Answer.

Short Answer Type Questions[l] [2 Marks] -Year 2011

27.What are the final products after digestion of carbohydrates and proteins?
Answer.The final product produced after digestion of carbohydrates is glucose and of proteins is amino acids.

28.What is saliva? State its role in the digestion of food.
Answer. Saliva is a watery fluid secreted by the salivary glands in the mouth. The digestive functions of saliva include moistening food, and helping to create a food bolus, so it can be swallowed easily. Saliva contains the enzyme amylase that breaks some starches down into maltose and dextrin.

29.Explain the process of nutrition in Amoeba.
Answer. Amoeba is an important protozoa found in fresh water. It feeds on microscopic plants and animals present in water. The mode of nutrition in amoeba is Holozoic. And the process of obtaining food by amoeba is called phagocytosis. The different processes involved in the nutrition of amoeba are:

1. Ingestion: Ingestion is the process of taking food in the body. Amoeba is a unicellular animal, so it doesn’t have a mouth for ingestion of food. Amoeba ingests the food by encircling it by forming pseudopodia. When the food is completely encircled , the food is engulfed in the form of a bag called food vacuole.
2. Digestion: Digestion is the process of breaking the large and insoluble molecules in small and water soluble molecules. In amoeba, several digestive enzymes react on the food present in the food vacuoles and break it down into simple and soluble molecules.
3. Absorption: The food digested by digestive enzymes is then absorbed in the cytoplasm by the process of diffusion. While the undigested food remains in the food vacuole. If a large amount of food is absorbed by amoeba, the excess food is stored in the cytoplasm ih the form of glycogen and lipids.
4. Assimilation: During this step the food absorbed by the cytoplasm is used to obtain energy, growth and repair. This process of utilizing absorbed food for obtaining energy, repair and growth is called assimilation.
5. Egestion: When a sufficient amount of undigested food gets collected in the food vacuole, it is thrown out of the body by rupturing cell membrane. The process of removal of undigested food from the body is called egestion.

30. State two differences between arteries and veins.
Answer. Arteries

1. Arteries carry oxygenated blood, away from the heart except pulmonary artery.
2. These are thick-walled, highly muscular except arteries of cranium and vertebral column.
3. Valves are absent.

Blood in arteries moves with pressure.Veins

1. Veins carry deoxygenated blood, towards the heart except pulmonary veins.
2. These are thin-walled.
3. Valves are present which provide unidirectional flow of blood.
4.  Blood in veins moves under very low pressure.

31. How are the alveoli designed to maximise the exchange of gases?
Answer.Alveoli are small pouches or sacs like structure. They are surrounded by blood capillaries. Thus a large amount of air is brought in contact with the air in the lungs. More than millions of alveoli are present in the lungs. The presence of millions of alveoli in the lungs provides a very large surface area for the exchange of gases. The availability of large surface area maximises the exchange of gases.

32. Name two excretory products other than 02 and CO₂ in plants.
Answer. The two excretory products other than 02 and CO₂ in plants are resins and gums.

Short Answer Type Questions[ll] [3 Marks] -Year 2011

33.(a) “The breathing cycle is rhythmic whereas exchange of gases is a continuous process”. Justify this statement.
(b) What happens if conducting tubes of circulatory system develops a leak? State in brief, how could this be avoided?
(c) How opening and closing of stomata takes place?
Answer. (a) The breathing cycle involves inhalation and exhalation of air due to alternate expansion and contraction of thoracic cavity. Thus it is a rhythmic process. But exchange of gases is a continuous process as it takes place between the blood and each and every cell, by diffusion.
(b) The circulatory system will become inefficient if it develops a leak. This could be avoided by maintaining a normal blood pressure.
(c) When water flows into the guard cells, the guard cells swell and the stomatal pore opens up. When water moves out the guard cells shrinks and the stomatal pore closes.

34. Draw a diagram of the front view of human heart and label any six parts including at least two, that are concerned with arterial blood supply to the heart muscles.
Answer.

Long Answer Type Questions [5 Marks] -Year 2011

35.(a) Draw a schematic representation of transport and exchange of oxygen and carbon dioxide during transportation of blood in human beings and label on it:
Lung capillaries, Pulmonary artery to lungs, Aorta to body, Pulmonary veins from lungs.
(b) What is the advantage of separate channels in mammals and birds for oxygenated and deoxygenated blood?
Answer.(a) A schematic representation of transportation and exchange of oxygen and
carbon dioxide during transportation of blood in human beings

(b) It is necessary to separate oxygenated and deoxygenated blood in mammals and birds because they need high energy and large amount of oxygen. The separation of oxygenated and deoxygenated blood provides high oxygen supply to the organs.

36.(a) Draw a diagram depicting Human Alimentary Canal and label on it: Gall bladder, Liver and Pancreas.
(b) State the roles of Liver and Pancreas.
(c) Name the organ which performs the following functions in humans:
(i) Absorption of digested food
(ii) Absorption of water.
Answer.(a)

(b) Liver: It synthesize and store bile juice secreted by gall bladder which breaks down fats into fat globules.
(c) The organ which performs the following functions in humans are as follows:
Pancreas: It secretes pancreatic juice which contains protein-digesting and starch- digesting enzymes. *
(i) Absorption of digested food – Small intestine.
(ii)Absorption of water – Large intestine.

37.(a) Draw a sectional view of the human heart and label on it – Aorta, Right ventricle and Pulmonary veins.
(b) State the functions of the following components of transport system:
(i) Blood (ii) Lymph
Answer.(a)

(b) The functions of blood and lymph are as follows:
(i) Blood

• Oxygen is transported by the blood to the tissues of the body for the breakdown of digested food.
• Carbon dioxide is transported to the lungs by the blood plasma.
• The digested and absorbed nutrients are transported by blood to the tissues. Nitrogenous wastes are transported to the kidneys.
• It regulates the body temperature and maintains the pH of the body tissues.
• It transports various hormones from one region to another and bring about the coordination.
• It maintains water balance to constant level.
• The lymphocytes produce antibodies against the invading antigens and protect from diseases.
• It helps in rapid healing of wounds by forming a clot at the site of injury.

(ii) Lymph

• It cleans the cellular environment.
• It returns proteins and tissue fluids to the blood (drainage)
• It provides a pathway for the absorption of fats and fat-soluble vitamins into the bloodstream.
• It defends the body against disease.

38.(a) Draw a labelled diagram of the respiratory system of human beings with diaphragm at the end of expiration.
(b) List four conditions required for efficient gas exchange in an organism.
Answer.(a)

(b) (i) A large surface area over which exchange can take place.
(ii) A concentration gradient without which nothing will diffuse.
(iii) A thin surface across which gases diffuse.
(iv) Warm conditions.

39.(a) Draw a diagram to show the nutrition in Amoeba and label the parts used for this purpose. Mention any other purpose served by this part other than nutrition.
(b) Name the glands associated with digestion of starch in human digestive tract and mention their role.
(c) How is required pH maintained in the stomach and small intestine?
Answer.(a)

Pseudopodia serves the purpose of locomotion apart from nutrition.
(b) The salivary gland is associated with digestion of starch in human digestive tract.
It secretes saliva which contains enzyme salivary amylase. This enzyme converts starch into maltose (sugar).
(c) Gastric glands present on the walls of the stomach release HC1. HC1 creates an acidic medium, which facilitates the action of enzyme pepsin. Bile juice from liver makes the food alkaline in small intestine for the pancreatic enzymes to act.

40. (a) Draw a labelled diagram of stomata. List two functions of stomata.
(b) What are the raw materials used during photosynthesis? Write chemical equation for photosynthesis.
Answer.(a)

(i) Gaseous exchanges between plant and the atmosphere.
(ii) Plant loses water through stomata which helps in movement of minerals from soil to leaves.
(b) Raw materials for photosynthesis: Carbon dioxide, water, chlorophyll and sunlight are the essential raw materials for photosynthesis.
(i) Carbon dioxide is a gas, which is released into the atmosphere during respiration. This gas is utilised by the autotrophic plants which enters the leaf through the stomata present on its surface during the process of photosynthesis.
(ii) Water is another requirement for photosynthesis, which is transported upward through xylem tissues to the leaves, from where it reaches the photosynthetic cells. This water then splits in the presence of sunlight and chlorophyll.
(iii) Chlorophyll is a green pigment in plants, which acts as a catalyst. It is responsible for absorption of the sun’s energy by the plant. The chlorophyll pigments are photoreceptor molecules which play a key role in the photosynthetic process. The different types of chlorophyll molecules are chlorophyll a, b, c, d, e and bacteriochlorophyll; of which chlorophyll a and b are the most common.
(iv) Light affects photosynthesis by its intensity, quality and duration. In green light, the rate of photosynthesis is minimum, while in red and blue lights the rate of photosynthesis is maximum.
Rate of photosynthesis is higher in plants getting average light of 10-12 hrs a day.
The chemical equation for photosynthesis is as follows:

41.(a) Leaves of a healthy potted plant were coated with vaseline to block the stomata. Will this plant remain healthy for long? State three reasons for your answer.
(b) State any two differences between autotrophic nutrition and heterotrophic nutrition.
Answer. (a) No, this plant will not remain healthy for long. The plant will begin to die because
(i) Gaseous exchange will not take place.
(ii) No absorption of C02, hence no photosynthesis.
(iii) Transpiration will not occur; hence no transportation of water.

Very Short Answer Type Questions [1 Mark] -Year 2010

42.Name the green dot like structures in some cells observed by a student when a leaf peel was viewed under a microscope. What is this green colour due to?
Answer. The green dot-like structures in some cells observed by a student when a leaf peel is viewed under a microscope are chloroplasts. The green colour is due to the presence of green pigment, chlorophyll.

43. State any one difference between autotrophic and heterotrophic modes of nutrition.
Answer. In autotrophic nutrition, organisms obtain their food from inorganic substances. In heterotrophic nutrition, organisms derive their food from organic substances.

44. A Give one reason why multicellular organisms require special organs for exchange of gases between their body and their environment. :
Answer. In unicellular organisms the entire body of the organism is in contact with the environment hence exchange of materials can take place but, in multicellular organisms the entire body of the organism is not in contact with the environment and hence simple diffusion is not helpful.

45. Name the process in plants where water is lost as water vapour. :
Answer. Transpiration is the process when plants loose water as vapour.

46. What is‘translocation’in plants?
Answer. Translocation is the movement of soluble materials, products of photosynthesis from leaves to other tissues throughout the plant.

47.State the basic difference between the process of respiration and photosynthesis.
Answer.

48. Name the intermediate and the end products of glucose breakdown in aerobic respiration.
Answer.

49. In the experiment “Light is essential for photosynthesis”, why does the uncovered part of the leaf turn blue-black after putting iodine solution?
Answer. Starch is produced in the uncovered part of the leaf because it is exposed to sunlight allowing it to photosynthesize, which turns blue-black in presence of iodine solution.

50.Name the component of blood that helps in the formation of blood clot in the event of a cut.
Answer. Platelets help in clotting of blood in the event of a cut.

51.Mention how organisms like bread moulds and mushrooms obtain their food.
Answer. Organisms like bread moulds and mushrooms breakdown the food materials outside the body and then absorb the nutrients of the bread.

Short Answer Type Questions[ll] [3 Marks] -Year 2010

52.Describe in brief the function of kidneys, ureters, urinary bladder and urethra.
Answer.The Kidneys filter the blood and concentrate the filtrate to make urine. They also help regulate blood pressure.
Ureters transport the urine to the urinary bladder.
Urinary bladder is like a holding tank for the urine until it’s ready to be excreted. Urethra is the tube that connects the urinary bladder to the outside of the body for excretion.

53. Explain the process of breakdown of glucose in a cell (ii) in the absence of oxygen.
Answer. The process of breakdown of glucose in a cell are as follows:

The first step in the breakdown of glucose both in presence of 02 and in absence of Os is same. In this step, glucose is broken down into pyruvate.
Second step which involves further breakdown of private into simple compounds can take place in two different ways:
(i) In presence of Oz: In the presence of 02, private is converted into C02 and water. Energy released during aerobic respiration is much greater than that released during an anaerobic respiration.
(ii)In absence of Oz: In the absence of 02 in yeast, pyruvate is converted into ethanol and C02 and the process is called fermentation. In absence of 02, in our muscle cells, pyruvate is converted into lactic acid. The build up of lactic acid in muscle cells causes cramps.

Long Answer Type Question [5 Marks] -Year 2010

54.(a) List the three events that occur during the process of photosynthesis.
Explain the role of stomata in this process.
(b) Describe an experiment to show that “sunlight is essential for photosynthesis.”
Answer.
(a) The three events that occur during the process of photosynthesis are:
(i) Absorption of light energy by the green pigment chlorophyll.
(ii) Conversion of light energy into chemical energy and the splitting of water molecule into hydrogen and oxygen.
(iii) Reduction of carbon dioxide into carbohydrate.
Role of Stomata
Stomata are tiny pores present on the surface of leaves. They are also present on the surface of young stems. Stomata are mainly engaged in the exchange of gases (entry of CO₂ and release of O₂ ) associated with photosynthesis. Plant closes the stomata when it does not need CO₂ for photosynthesis.
(b) Sunlight is essential for photosynthesis

Procedure:
(i) Place a healthy green potted plant in a dark room for 1-2 days. This is done to ensure
that the plant consumes all its reserve food and the leaves do not contain any starch.
(ii) Then, cover a portion of a leaf of this plant on both sides with two uniform pieces of black paper, fixed in position with two paper clips.
(iii) Now, expose this plant to bright light. After a few hours, remove the leaf and decolorize it with alcohol and test the presence of food (starch) with iodine solution.
Observation: It can be observed that the portion of the leaf covered with black paper does not (food),
Conclusion: This is because the food prepared by plants through the process of photosynthesis is stored as starch. Starch reacts with the iodine solution to give blue-black colour. Only those portions of the leaf that were exposed to sunlight could photosynthesise. Hence, gives blue- black colour when tested with iodine. The portion of the leaf covered with black paper did not receive sunlight. Hence, starch was not produced. Thus, it can be
concluded that the sunlight is essential for photosynthesis.

Very Short Answer Type Questions [1 Mark] -Year 2009

55. What will happen to a plant if its xylem is removed?
Answer. Xylem in plant transports water and dissolved mineral nutrients from the roots to all parts of the vascular plant. So, if xylem is removed from the plant, the water and mineral supply to the plant will stop and therefore, the plant will die.

56. Where does digestion of fat take place in our body?
Answer. Digestion of fat takes place in the small intestine of our body.

57. What is the mode of nutrition in human beings?
Answer. Holozoic nutrition.

Long Answer Type Questions [5 Marks] -Year 2009

58.(a) What is meant by breathing? What happens to the rate of breathing during
vigorous exercise and why?
(b) Define translocation with respect to transport in plants. Why is it essential for plants? Where in plants are the following synthesised?
(i) Sugar (iii) Hormone
Answer.(a) The process of taking in of oxygen from air in to the lungs and expulsion of carbon dioxide out of the lungs is called breathing. The rate of breathing during vigorous exercise increases by about 20 to 25 times per minute. It is because, during vigorous exercise the demand for oxygen increases. Breathing occurs involuntarily but its rate is controlled by the respiratory center of the brain.
(b) Translocation is the transport of food from the leaves to other parts of the plant and occurs in the part of the vascular tissue known as phloem.
It is essential for plants because every part of the plant needs food for obtaining energy for building its parts and maintaining its life.
(i) Sugar is synthesised in the leaves of the plant.
(ii) Hormones are synthesised at the tips of roots and stems of a plant.

59.(a) Draw the structure of a nephron and label the following on it:
Glomerulus, Bowman’s capsule, Renal artery, Collecting duct.
(b) What happens to glucose that enters the nephron along with filtrate?
Answer.(a)

(b) During excretion in human beings, glucose which enters the nephron along with filtrate gets reabsorbed by blood capillaries surrounding the nephron.

Important QuestionsNCERT SolutionsSample PapersNCERT Exemplar Solutions

The post Life Processes Chapter Wise Important Questions Class 10 Science appeared first on Learn CBSE.

Download Formula BookPhysics eBookChemistry eBookBiology eBook

Control  and Coordination Chapter Wise Important Questions Class 10 Science

Very Snort Answer Type Question [1 Mark] -Year 2015

1.Why is it advised to use iodised salt in our diet ?
Answer. Iodine stimulates the thyroid gland to produce thyroxin hormone. Deficiency of this hormone results in the enlargement of the thyroid gland. This can lead to goitre.

Short Answer Type Questions[ll] [3 Marks] -Year 2015

2.State how concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light ?
Answer. When light falls on the side of the shoot auxin diffuses towards the shady side of the shoot. This concentration of the auxin stimulates the cell to grow longer on the side of the shoot which is away from light. Thus plant appears to bend towards light.

3. What is synapse ? In a neuron cell how is an electrical impulse created and what is the role of synapse in this context ?
Answer. A synapse is the gap between the two neurons. Here the axon terminal of one neuron is in close proximity to the dendrite of the second neuron. When a nerve impulse reaches the knob like nerve ending of an axon, a tiny amount of a chemical substance is released in the synapse. This chemical substance is called as the neurotransmitter. At synapse the electrical signals converted into chemicals, that can easily cross over the gap and pass on to the next neurons where it again converted into electrical signals.

Long Answer Type Question [5 Marks] – Year 2015

4. What is meant by reflex-action ? With the help of a labelled diagram trace the sequence of events which occur when we touch a hot object.
Answer.Stimulus: In the example above, the stimulus is the contact with the hot pot. This contact causes a nerve impulse that will travel to the spinal cord via the sensory neurons.
Sensory neurons: These neurons carry the nerve impulse to the spinal cord. Similar to the interneuron and motor neuron, sensory neurons receive incoming impulses at the dendrites. The impulses move away from the cell body along the axon to the synaptic terminal where the impulse is sent to the next interneuron with the help of a neurotransmitter (acetylcholine). Interneurons: The interneuron is also known as relay neuron. These neurons are fully contained in the central nervous system. The interneuron serves as the connection between the sensory neurons and the motor neurons. Synapse: The synapse is a tiny space between two neurons. When an impulse gets to the end of one neuron and has to be sent down to the next neuron, the synapse acts as a bridge. The signal arrives at the end of one neuron (close to the synapse) as an electrical signal, crosses the synapse as a chemical signal (with the help of a neurotransmitter known as acetylcholine released by the synaptic vesicles at the synaptic terminal) and continues as an electrical signal in the next neuron.
Motor neurons: These neurons send nerve impulses away from the central nervous system to effector organs or muscle fiber in our example above. This causes the muscle fiber to contract, resulting in you snatching your hand away from the hot pot.

Response: To respond to the stimulus of the reflex arc, the muscle needs to contract to pull the hand quickly away from the hot pot. For this to happen, the impulse travels to the synaptic terminal of the motor neuron. Synaptic vesicles at the synaptic . terminal will then release acetylcholine which will cross the synapse and bind to the receptors on the muscle fibers to trigger the muscle contraction known as the ‘response’.

Very Short Answer Type Question [1 Mark]- Year 2014

5. Give an example of a plant hormone that promotes its growth. Where it is synthesized ?
Answer. Plant hormone that promotes growth is auxin. It is synthesized at the tip of the plant stem.

Short Answer Type Question [I] [2 Marks] – Year 2014

6.(i) Name the hormones that are released in human males and females when they reach puberty.
(ii) Name a gland associated with brain. Which problem is caused due to the deficiency of the hormone released by this gland ?
Answer.
(i) Testes in males produces hormone testosterone.
Ovaries in females produces hormone oestrogen.
(ii)Pituitary gland present in the brain is responsible for body growth, development of bones and muscles (if excess-gigantism) (if less-dwarfism).

Short Answer Type Questions[ll] [3 Marks] – Year 2014

7. Draw neat diagram of human brain and label on it the following parts :
(i) Midbrain (ii) Pituitary gland
Answer.

8.Write one example each of the following tropic movements :
(i) Positive phototropism (ii) Negative phototropism
(iii) Positive geotropism (iv) Negative geotropism
(v) Hydrotropism (vi) Chemotropism
Answer.
(i) Positive phototropism: shoots growing towards light.
(ii)Negative phototropism: roots growing away from light towards ground.
(iii) Positive geotropism: growth of roots towards earth due to the pull of the earth.
(iv)Negative geotropism: shoots growing away from the earth.
(v) Hydrotropism: roots growing towards the source of water.
(vi)Chemotropism: growth of pollen tubes towards the ovules.

Long Answer Type Questions [5 Marks] – Year 2014

9.(a) Name the hormone which is released into the blood when its sugar level rises. Explain the need of Chemical communication in multicellular organisms the organ which produces this hormone and its effect on blood sugar level. Also mention the digestive enzymes secreted by this organ with one function of each.
(b) Explain the need of Chemical communication in multicellular organisms.
Answer.
(a) Glucose is needed by cells for respiration. It is important that the concentration of glucose in the blood is maintained at a constant level. Insulin is a hormone produced by the a-cells that regulates glucose levels in the blood.
In order for multicellular organisms to function properly, their cells must communicate. For instance, your muscles must contract when your brain sends a message to contract.
Pancreas produces insulin and p-cells which increase glucose in blood. It also – produces digestive enzyme (pancreatic amylase).
(b) Cell-to-cell signaling is a critical component of coordinating cellular activities. Through this communication, messages are carried from signaling cells to receiving cells, also known as target cells. This signaling occurs with proteins and other types of signaling molecules. Other things which happens in our body due to cell communication are – growth and development, cellular reproduction, tissue repair, sensing pain, etc.

10.State the structural and the functional unit of the nervous system. Draw its neat labelled diagram and write two functions.
Answer. The structural and functional unit of the nervous system is the neuron.

The functions of the neuron are:
(a) Passing of information takes place-
(i) By electric impulse (inside the neuron) and
(ii) In the form of chemicals (At synapse)
(b) Reflex action- spontaneous, involuntary and automatic response to a stimulus to protect us from harmful situations. For example, on touching a hot object unknowingly we instantly withdraw our hand.

Very Short Answer Type Question [1 Mark] -Year 2013

11.State the function of:
(i) gustatory receptors, and
(ii) olfactory receptors.
Answer.
(i) Gustatory receptors – these are sensitive to taste
(ii) Olfactory receptors – these are sensitive to smell.

Short Answer Type Questions[ll] [3 Marks] -Year 2013

12.(a) Explain any three directional movements in plants.
(b) How brain and spinal cord are protected in human ?
(c) Name the master gland present in the brain.
Answer.
(a) Stimuli is responsible for the movement of the plant parts towards or away from it. This movement is called as Tropic Movement.
Phototropism: movement of plant towards or away from the light. Geotropism: movement of plant parts towards the earth or away from it. Hydrotropism: movement of plant parts towards or away from any source of water.
(b) Both the brain and the spinal cord are protected by bone: the brain by the bones of the skull and the spinal cord is protected by a set of ring-shaped bones called vertebrae. They are both cushioned by layers of membranes called meninges as well as a special fluid called cerebrospinal fluid. This fluid helps to protect the nerve tissue to keep it healthy, and remove waste products.
(c) Pituitary gland present in the brain is known as the master gland.

13. List in tabular form three differences between nervous control and chemical control.
Answer.

Very Short Answer Type Questions [1 Mark] -Year 2012

14. Name the part of the brain which controls posture and balance of the body. 
Answer.Cerebellum in hind-brain controls the posture and balance of the body.

15. Mention the part of the body where gustatory and olfactory receptors are located.
Answer. Gustatory receptors are located in Cerebrum of fore-brain. Olfactory receptors are located in Olfactory lobe of fore-brain.

16. Smita’s father has been advised by a doctor to reduce his sugar intake.

1. Name the disease he is suffering from and name the hormone whose deficiency is? ,
2. Identify the gland that secretes it and mention the function of this hormone.
3.  Explain how the time and amount of secretion of this hormone is regulated in human system.

Answer.

1.  He is suffering from diabetes. Deficiency of insulin causes diabetes.
2. Pancreas secretes insulin. Insulin helps in regulating blood sugar.
3. When the sugar level in blood increases, it is detected by the a-cells of the pancreas which responds by producing more insulin. As the blood sugar level falls, insulin secretion is reduced.

17.State the functions of plant hormones. Name four different types of plant hormones.
Answer. Plant hormones help to coordinate growth, development and responses in environment.
Four different types of plant hormones are – Auxins, Gibberellins, Cytokinins, Ethylene and Abscisic acid.

1. Auxins control the tropic (growth related) movements of the plants in response to light, gravity, touch etc by increasing the size of cells. Under the influence of auxins, the plant stem bends towards unidirectional light where as the roots bend away from it.
2. Gibberellins stimulate stem elongation and leaf expansion. Its application causes stem elongation in small plants such as cabbage. Spraying gibberellins on sugarcane plant increases the stem size and hence the yield.
3. Cytokinins are produced in regions of the plant body where rapid cell division occur, such as root tips, developing shoot buds, young fruits and seeds. Cytokinins promote growth by stimulating cell division. They also help in production of new leaves and chloroplasts in leaves.
4. Ethylene causes ripening of the fruits.
5. Abscisic acid inhibits (i.e., slows down) the growth in different parts of the plant body. It also inhibits germination of seeds. It increases the tolerance of plant to different kinds of stresses such as temperature changes. So, it is also called the stress hormone in plants. It also causes the drying and falling of older leaves, flowers and fruits.

18.(a) How is brain protected from injury and shock?
(b) Name two main parts of hind brain and state the functions of each.
Answer.
(a) Brain is covered by a three layered membrane called meninges. In between the layers of meninges and brain, cavity fluid named Cerebro Spinal Fluid (CSF) is filled. The hard skull covers the meninges. Thus Meninges, CSF and Skull protects our brain for a certain extent.
(b) Two main parts of hind-brain are — Medulla and Cerebellum. Their functions are:
Medulla : Involuntary actions such as blood pressure, salivation and vomiting.
Cerebellum : It is responsible for precision of voluntary actions and maintaining the posture and balance of the body.

19.(a) Draw the structure of neuron and label cell body and axon.
(b) Name the part of neuron:
(i) where information is acquired
(ii) through which information travels as an electrical impulse.
Answer.

(a) A nerve cell (Neuron)
(b) (i) Dendrite (ii) Axon

20.(a) Which plant hormone is present in greater concentration in the areas of rapid cell division?
(b) Give one example of a plant growth promoter and a plant growth inhibitor.
Answer.
(a) Cytokinin is present in greater concentration in the areas of rapid cell division.
(b) An example of a plant growth promoter is gibberellins and example of a plant growth inhibitor is abscisic acid.

Short Answer Type Questions[ll] [3 Marks] -Year 2011

21.Which organ secretes a hormone when bloo’d sugar rises in our body? Name the hormone and name one enzyme released by this organ.
Answer.Pancreas secretes a hormone when blood sugar rises in our body. Insulin is the hormone released by this organ and the name of the enzyme is pancreatic juice.

22.(a) Explain how auxins help in bending of plant stem towards light.
(b) State the objective of the experiment for which experimental set-up is shown in the given diagram.
Answer.
(a) In plant shoots, the role of auxin is to cause a positive phototropism, i.e. to grow the plant towards the light. When light is incident on a plant from one direction, it causes the auxins to redistribute towards the shaded side of the plant. One function of auxin is to cause cell elongation. The redistribution causes the cells on the shaded side to elongate more than those on the side with the light shining on them. This causes the shoot to bend towards the light.
(b) The objective of the experiment is to show phototropic movement of plant.

23.What causes a tendril to encircle or coil around the object in contact with it is? Explain the process involved.
Answer. When a tendril comes in contact with any support, the part of the tendril in contact with the object does not grow as rapidly as the part away of the tendril away from the object. This cause the tendril to circle around the object and thus, cling to it.

24. Name any three endocrine glands in human body and briefly write the function of each of them.
Answer.Three endocrine glands with their function in human body are as follows:

1. Thyroid gland : It secretes a hormone called thyroxine which regulates the metabolism of carbohydrates, fats and proteins in the body and so provide the best balance for nutrients and mental ability.
2. Adernal gland : It secretes two hormones—adrenalin and corticoid hormones regulate blood pressure, heartbeat, breathing rate and carbohydrate metabolism.
3.  Pancreas: It secretes two hormones—insulin and glucagon. Insulin hormone lowers the blood glucose level. Glucagon hormone increases the blood glucose level.

25. Which part of the brain controls involuntary actions? Write the function of any two regions of it. Answer. Hind-brain controls the involuntary actions. Cerebellum controls the coordination of body movement and posture. Medulla oblongata regulates center for swallowing, coughing, sneezing and vomiting.

26. What is chemotropism? Give one example. Name any two plant hormones and mention their functions.
Answer. Chemotropism is the movement of a part of the plant in response to a chemical stimulus. It can be positive chemotropism or negative chemotropism. Example: The growth of pollen tube towards a chemical which is produced by an ovule during the process of fertilisation in a flower.
Two plant hormones with their functions are as follows:
Auxins promote cell elongation, root formation, cell division, respiration and other physiological processes like protein synthesis, etc.
Gibberellins stimulate stem elongation, seed germination and flowering.

27. State the functions of any three of the structural and functional unit of nervous system.
Answer. The structural and functional unit of nervous system, i.e. neuron with their functions are as

1. Cell body: Stimulus received from dendrite is changed into impulse in the cyton.
2. Dendrites: They receive sensation or stimulus, which may be physical or chemical.
3. Axon: It conducts impulse away from the cell body.

28. What is ‘hydrotropism’? Describe an experiment to demonstrate ‘hydrotropism’.
Answer. ‘Hydrotropism’ is the directional growth of a plant part in response to water. For example, roots show hydrotropism as they grow towards water in the soil and are positively hydrotropic.
An experiment to demonstrate hydrotropism is as follows:

1.  A porous pot filled with water is taken and inserted in a tub filled with dry sand.
2. A freshly germinated pea seedling is sowed in the sand.
3. As water is not available in sand, the root growing will bend towards the porous pot filled with water.
4. A hydrotropic curvature of the root is observed as it grows towards water.
5. This bending of root shows the movement in response towards water.

29. What are ‘hormones’? State one function of each of the following hormones:
(i) Thyroxine (ii) Insulin
Answer. Hormones are the chemical substances which coordinate and control the activities of living organisms and also their growth. The term hormone was introduced by Bayliss and Starling.
(i) Function of Thyroxine: This hormone regulates the metabolism of carbohydrates and fats.
(ii) Function of insulin: This hormone helps in regulating sugar level in the blood.

30. What is the function of receptors in our body? Think of situation where receptors do not work properly. What problems are likely to arise?
Answer. Receptors are present in our all parts of the body for example in skin, eye, nose tongue etc. They detect the signals and then send them to brain in the form of electrical signals. If these receptors are damaged then it they will not detect the input which leads to the harm for our body in dangerous situation.

Very Short Answer Type Questions [1 Mark] -Year 2010

31. How is the spinal cord protected in the human body?
Answer.Spinal cord is enclosed in a bony cage called vertebral column.

32. A potted plant is made to lie horizontally on the ground. Which part of the plant will show
(i) positive geotropism?
(ii) negative geotropism?
Answer.
(i) Root (ii) Shoot.

33. Mention the function of the hind-brain in humans.
Answer.Hind brain controls respiration, cardio-vascular reflexes and gastric secretions.
It also modulates the motor commands initiated by the cerebrum.

34. Mention the function of adrenaline hormone.
Answer. Adrenaline hormone is released into the blood from the adrenal gland during stimulation of the nervous system on seeing any adverse situation of fight or fright, it:

1. increases the blood pressure.
2. increases heart beat rate.
3. increases breathing rate.
4. diverts blood to essential organs including the heart, brain and skeletal muscles by dilating their blood vessels and constricting those of less essential organs, such as the skin and digestive system.

Short Answer Type Questions[l] [2 Marks] -Year 2010

35. Name, the two main organs of our central nervous system. Which one of them plays a major role in sending command to muscles to act without involving thinking process? Name the phenomenon involved.
Answer.The two main organs of CNS are brain and spinal cord.
Spinal cord plays a major role in sending command to muscles to act without involving thinking process. This phenomenon is called reflex action.

36.Name the hormone secreted by human testes. State its functions.
Answer. Testes secrete male sex hormone called testosterone. The function of testosterone is to regulate male accessory sex organs and secondary sexual characters like moustache, beard and voice.

37.Name and explain the function of the hormone secreted by the pituitary gland in humans.
Answer. Hormones secreted by pituitary gland alongwith their functions are:

1. Grpwth hormone: It regulates growth and development ofbones and muscles.
2. Trophic hormone: It regulates secretion of hormones from other endocrine glands.
3.  Prolactin hormone: It regulates the function of mammary glands in females.
4.  Vasopressin hormone: It regulates water and electrolyte balance in the body,
5. Oxytocin hormone : It regulates ejection of milk during lactation.

Short Answer Type Questions[ll] [3 Marks] -Year 2010

38.What is a reflex action? Describe the steps involved in a reflex action.
Answer.
Reflex action: Jt is defined as an unconscious, automatic and involuntary response of effectors, i.e. muscles and glands, to a stimulus, which is monitored through the spinal cord.
Mechanism of reflex action : It involves the following steps:

1. Receptor organ like skin perceives the stimulus and activates a sensory nerve impulse.
2. Sensory organ carries message in the form of sensory impulse to the spinal cord.
3. The spinal cord acts as modulator : The neurons of spinal cord transmit the sensory nerve impulse to motor neuron.
4. Motor never conducts these impulses to the effectors like leg muscles which responds by pulling back the organ away from the harmful stimulus.

39.List the components of reflex arc in correct sequence. State in brief the role of brain in reflex action.
Answer. The reflex arc pathway is shown in the flow chart as follows:
The Reflex arc does not involve brain. It minimises the overloading of brain.

Very Short Answer Type Questions [1 Mark] -Year 2009

40. A young green plant receives sunlight from one direction only. What will happen to its shoots ?
Answer. Shoots will bend towards the light and roots away from the light.

41. Name the plant hormones which help/promote (i) cell division (ii) growth of
the stem and roots?
Answer. The plant hormones which help or promote:
(i) Cell division — Cytokinins
ii) Growth of the stem — Gibberellins

42. What is the function of thyroxine hormone in our body ? jlMluK r
Answer. Thyroxine hormone regulates the carbohydrate, protein and fat metabolism in the body so as to provide the best growth balance.

43. Name two tissues that provide control and coordination in multicellular animals.
Answer. The two tissues that provide control and coordination in multicellular animals are nervous and muscular tissues.

44. Which one of the following actions on touch is an example of chemical control?
(i) Movement on the touch-sensitive plant.
(ii) Movement in human leg.
Answer.
(i) Movement on the touch-sensitive plant.

Short Answer Type Questions[l] [2 Marks] -Year 2009

45.What are ‘nastic’ and ‘curvature’ movements? Give one example of each.
Answer. Nastic movements: These are non-directional movements which are neither towards nor away from the stimulus. Example: Dropping of leaves.
Curvature movements: In such movements plant organs move towards or away from the stimulus. Example: Bending of shoot towards a source of light.

46.Write the name and functions of any two parts of the human hind-brain.
Answer.Any two parts of human hind-brain with their functions are as follows:
(i) Cerebellum, which controls the coordination ofbody movement and posture. (ii) Medulla oblongata, which regulates the centre of swallowing, coughing, sneezing and vomiting.

47. What are plant hormones? Write two important functions of auxin. 
Answer. Plant hormones can be defined as a chemical substance which is produced naturally in plants and are capable of translocation and regulating one or more physiological processes when present in low concentration. .
Two important functions of auxin are that it promotes cell elongation, root formation, cell division, etc.

Short Answer Type Question[ll] [3 Marks] -Year 2009

48.(a) Name the two main constituents of the Central Nervous System in human beings.
(b) What is the need for a system of control and coordination in human
beings?
Answer.(a) The two main constituents of the Central Nervous System in human beings are the brain and the spinal cord.
(b) A living being does not live in isolation. It has to constantly interact with its external environment and has to respond properly for its survival. For example; when a hungry lion spots a deer, the lion has to quickly make a move so that it can have its food. On the other hand, the deer needs to quickly make a move to run for its life. The responses which a living being makes in relation to external stimuli are controlled and coordinated by a system; especially in complex animals. So, control and coordination . is essential in maintaining a state of stability and a steady state between the internal conditions of an organism and the external environment.

Important QuestionsNCERT SolutionsSample PapersNCERT Exemplar Solutions

The post Control and Coordination Chapter Wise Important Questions Class 10 Science appeared first on Learn CBSE.

Electricity  Chapter Wise Important Questions Class 10 Science

Important QuestionsNCERT SolutionsSample PapersNCERT Exemplar Solutions

Very Short Answer Type Questions [1 Mark] – Year 2015

1. Write S.I. unit of resistivity.
Answer. Ohm-metre (Ωm).

Short Answer Type Questions[ll] [3 Marks] – Year 2015

2.(i) Draw a closed circuit diagram consisting of a 0.5 m long nichrome wire XY, an ammeter, a voltmeter, four cells of 1.5 V each and a plug key.
(ii)Following graph was plotted between V and I values :

What would be the values of V /I ratios when the potential difference is 0.8 V, 1.2 V and 1.6 V respectively? What conclusion do you draw from these values?
Answer.

3.Study the following electric circuit and find (i) the current flowing in the circuit and (ii) the potential difference across 10 Ω resistor.

Answer.

4. Find the current drawn from the battery by the network of four resistors Shown in the figure.

Answer.

Long Answer Type Questions [5 Marks] – Year 2015

5. What is meant by electric current? Name and define its SI unit. In a conductor electrons are flowing from B to A. What is the direction of conventional current? Give justification for your answer.
A steady current of 1 ampere flows through a conductor. Calculate the number of electrons that flows through any section of the conductor in 1 second. (Charge on electron 1.6 X 10-19 coulomb).
Answer.

• Electric Current: The amount of charge ‘Q’ flowing through a particular area of cross section in unit time ‘t’ is called electric current, i.e.
• Electric current, I = Q/t
•  SI unit of electric current is ampere.
•  One ampere of current is that current which flow when one coulomb of electric charge flowing through a particular area of cross-section of the conductor in one second, i.e. 1A = 1 Cs^-1.
•  The direction of conventional current is A to B, i.e. opposite to the direction of flow of electrons. In a metal, flow of electrons carrying negative charge constitutes the current. Direction of flow of electrons gives the direction of electronic current by convention, the direction of flow of positive charge is taken as the direction of conventional current.
  Charge = q = ne
  

6.What is meant by electrical resistivity of a material? Derive its S.I. unit. Describe an experiment to study the factor on which the resistance of a conducting wire depends.
Answer. Mathematically, resistivity of the conducting material is given by
p = R x A/J
If l = 1 m, A = 1 m², then p = R
Hence, the resistivity of the material is defined as the resistance offered by a metallic wire having a unit length and a unit area of cross-section. Since unit length and unit area of cross-section forms a cube, the specific resistance or resistivity can also be defined as the resistance offered by a cube of a material of side 1 m when current flows perpendicularly through the opposite faces. In SI system, its units is

Experiment:
Aim : To study the factors on which resistance of conducting wires depends. Apparatus Required : A cell, an ammeter, nichrome wires of different length but same area of cross-section (thickness), nichrome wires of same length but different thickness, copper and iron wire of the same length and same thickness as that of any nichrome wire.
Procedure :

1. Connect the cell, an ammeter and plug key in series with nichrome wire of length T (marked 1) in the gap XY as shown.
   
2. Close the key and note the reading of ammeter. It measures the current ‘I’₁ through the nichrome wire (marked ‘1’).
3. Replace the marked 1 wire with another nichrome wire having same area of cross-section (thickness) but of double length’2l’ (marked 2).
4. Note the ammeter reading (I₂) again after closing the key.
5. Again replace the marked 2 wire with marked 3 wire which has the same length but is thicker than marked 1 and 2 nichrome wires. Again note down the current (I₃) through this wire.
6. Unplug the key. Remove marked 3 nichrome wire from the gap XY. Connect the copper wire marked 4 having same length and same area of cross-section as that of nichrome wire marked 1. .
7. Plug the key again and note the ammeter reading. It measures the current (I₄) through copper wire.
8. Repeat the experiment with iron wire and measure the current (I₅).

Observation :

1. Current ‘ I’ is half ofI₁ i.e., I₂ =1/2 I₁
2. Current I₃ increases when thicker wire of same length and of same material
   i. e., nichrome is used.
3. Current I₄ and I₅ is different for copper and iron wire.

Conclusion :

1. Different wires drew different amount of current from the same cell.
2. First observation indicates that the resistance of the conductor increases with increase in length. So, resistance is directly proportional to length.
3. Second observation shows that thicker wires have lesser resistance. So, resistance is inversely proportional to area of cross section of the wire.
4. Third observation shows that resistance of the conductor depends on the nature of its material.

7. (a) Write two points of difference between electric energy and electric power. (6) Out of 60 W and 40 W lamps, which one has higher electrical resistance when in use.
(c) What is the commercial unit of electric energy? Convert it into joules.
Answer. (a) Difference between electric energy and electric power:

i.e. less the power of electrical device, higher is its electrical resistance.
(c) Kilowatt hour – Commercial unit of electrical energy
1 kWh = 1000 Wh = 1000 J/S x 3600 sec
= 3600000 J = 3.6 x10⁶J

8.State Ohm’s law. Write the necessary conditions for its validity. How is this law verified experimentally? What will be the nature of graph between potential difference and current for a conductor? Name the physical quantity that can be obtained from this graph.
Answer. Ohm’s law : When the physical conditions such as temperature etc. remain same, the current flowing through the conductor is directly proportional to the potential difference applied across the ends of the conductor, i.e.,

Necessary condition for validity of Ohm’s law is that physical condition such as
temperature of the conductor remains same.
Procedure:
(i) Complete the circuit by connecting one cell in the gap XY. Plug the key.

(ii) Note the reading in the ammeter for the current I and in the voltmeter for the potential difference, (V) across the nichrome wire.

(v) Find the ratio of F to / for each observation.
(vi) Plot a graph between V (y-axis) and I (x-axis).
Observation :

1. Voltmeter and ammeter reading increases as the number > of cells increase in series.
2. Same value of V/I is obtained in each case.
3.  V-I graph is a straight line passing through the origin of the graph as shown.
   

Conclusion : Straight line nature of graph shows that the current is proportional to the potential difference. Hence, Ohm’s law verified. The slope of V-I graph gives the value of resistance of the conductor at the given temperature.

Very Short Answer Type Question [1 Mark] – Year 2014

9. Name a device that helps to maintain a potential difference across a conductor.
Answer. Cell or battery

Short Answer Type Questions [II] [3 Marks] – Year 2014

10.Define 1 volt. Express it in terms of SI unit of work and charge calculate the amount of energy consumed in carrying a charge of 1 coulomb through a battery of 3 V.
Answer.When 1 joule of work is done in carrying 1 coulomb of charge, from infinity to a point in the electric field, then potential at that point is called 1 volt. Potential difference between two points is

11. V-I graph for two wires A and B are shown in the figure. If both wires are of same length and same thickness, which of the two is made of a material of high resistivity? Give justification for your answer.

Answer. Greater than slope of V-I graph, greater will be the resistance of given metallic wire. In the given graph, wire A has greater slope then B. Hence, wire A has greater resistance.
For the wires of same length and same thickness, resistance depends on the nature of material of the wire, i.e.

Long Answer Type Questions [5 Marks] – Year 2014

12.Draw a labelled circuit diagram showing three resistors R₁, R₂ and R₃ connected in series with a battery (E), a rheostat (Rh), a plug key (K) and an ammeter (A) using standard circuit symbol. Use this circuit to show that the same current flows through every part of the circuit. List two precautions you would observe while performing the experiment.
Answer.

Aim: Same current flows through every part of the above circuit.
Procedure:

1. Connect ammeters, ‘A’₁ between B and C, and ‘A₂’ between D and E.
2.  Adjust the sliding contact of the rheostat initially for a small current.
3. Note all the ammeter readings. These reading give us current flowing through the resistors R₁, R₂ and R₃
4. The current in the circuit is now increased by changing the position of sliding contact J’ of the rheostat.
5. Note all the ammeter readings each time.

Conclusion: Same reading of all the ammeter in each observation concluded that same current flows through every part of the circuit.

Precautions:

1. All the connection should be tight and properly connected as per circuit diagram.
2. The positive terminal of the ammeter and voltmeter must be connected to the positive terminal of the battery or battery eliminator.

13.Two wires A and B are of equal length and have equal resistance. If the resistivity of A is more than that of B which wire is thicker and why? For the electric circuit given below calculate:

(i) Current in each resistor,
(ii) Total current drawn from the battery, and
(iii) Equivalent resistance of the Circuit
Answer.

So, for different materials having same resistance per unit length, greater resistivity material wire has more cross-sectional area.
Hence, wire A is thicker than that of B.
(i) Current through each resistor

14. (a) Define electric power. Express it in terms of potential difference V and resistance R.
(b) An electrical fuse is rated at 2 A. What is meant by this statement?
(c) An electric iron of 1 kW is operated at 220 V. Find which of the following fuses that respectively rated at 1 A,3 A and 5 A can be used in it.
Answer.
(a) Electric power: It is the rate of doing work by an energy source or the rate at which the electrical energy is dissipated or consumed per unit time in the electric circuit is called electric power.

(b) It means, the maximum current will flow through it is only 2 A. Fuse wire will melt if the current exceeds 2 A value through it.

Very Short Answer Type Questions [1 Mark] – Year 2013

15. Write relation between heat energy produced in a conductor when a potential difference V is applied across its terminals and a current I flows through for ‘t’
Answer. Heat produced, H = VIt

16. State difference between the wire used in the element of an electric heater and in a fuse wire.
Answer. The wire used in the element of electric heater has a high resistivity and have a high melting point, i.e. even at a high temperature element do not burn while fuse wire have a low melting point and high resistivity.

Short Answer Type Questions [3 Marks] – Year 2013

17.The figure below shows three cylindrical copper conductors along with their face areas and lengths. Discuss in which geometrical shape the resistance will be highest.

Answer.

18.Find the current flowing through the following electric circuit.

Answer.

19. An electric bulb of resistance 200Ω draws a current of 1 Ampere. Calculate the power of the bulb the potential difference at its ends and the energy in kWh consumed burning it for 5h.
Answer. Power of the bulb,

Long Answer Type Questions [5 Marks] – Year 2013

20. (a) Calculate the resistance of 1 km long copper wire of radius 1 mm. Resistivity of the copper is 1.72 x 10^-8 Ω m.
(b) Draw a schematic diagram of a circuit consisting of a battery of 4 cells of
2V each connected to a key, an ammeter and two resistors of 2 Ω and
3 Ω respectively in series and a voltmeter to measure potential difference across 3
Answer.

21.When a high resistance voltmeter is connected directly across a resister its reading is 2 V. An electric cell is sending the current of 0.4 A, (measured by an ammeter) in the electric circuit in which a rheostat is also connected to vary the current.
(a) Draw an equivalent labelled circuit for the given data.
(b) Find the resistance of the resister.
(c) Name and state the law applicable in the given case. A graph is drawn between a set of values of potential difference (V) across the resister and current (I) flowing through it. Show the nature of graph thus obtained.
Answer.

(c) Ohm’s law : When the physical conditions such as temperature etc. remain same, the current flowing through the conductor is directly proportional to the potential difference applied across the ends of the conductor, i.e.,

where R is constant of proportionality and is called resistance of the wire. Since current varies linearly with potential difference, the graph between V and I will be a linear in nature as shown

Short Answer Type Questions[l] [2 Marks] – Year 2012

22. How much current will an electric bulb draw from 220 V source if the resistance of the bulb is 1200Ω? If in place of bulb, a heater of resistance 100 Ω is connected to the sources, calculate the current drawn by it.
Answer.

23.Draw a schematic diagrams of an electric circuit comprising of 3 cells and an electric bulb, ammeter, plug-key in the ON mode and another with same components but with two bulbs in parallel and a voltmeter across the combination.
Answer.

24. Out of the two wires X and Y shown below, which one has greater resistance? Justify your answer.

Answer. Wire ‘Y’ has greater resistance as it has more length than wire ‘X’. It is because resistance of wire is directly proportional to the length of wire.

Short Answer Type Questions[ll] [3 Marks] – Year 2012

25. Two identical wires one of nichrome and other of copper are connected in series and a current (I) is passed through them. State the change observed in the temperatures of the two wires. Justify your answer. State the law which explains the above observation.
Answer. The resistivity of nichrome is more than that of copper so its resistance is also high. Therefore, large amount of heat is produced in the nichrome wire for the same current as compared to that of copper wire. Accordingly, more change in temperature is observed in the nichrome wire. This is explained by Joule’s law of heating.
Joule’s law of heating: It states that the amount of heat produced in a conductor is

26.An electric bulb is rated at 60 W, 240 V. Calculate its resistance. If the voltage drops to 192 V, calculate the power consumed and the current drawn by the bulb. (Assume that the resistance of the bulb remain unchanged.)
Answer.

Current drawn by bulb at 192 V is

Long Answer Type Questions [5 Marks] – Year 2012

27. Three bulbs each having power P are connected in series in an electric circuit. In another circuit, another set of three bulbs of same power are connected in parallel to the same source.
(i) Will the bulbs in both the circuits glow with the same brightness? Justify your answer.
(ii) Now let one bulb in each circuit get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason.
(iii) Representing each bulb by a resistor, draw circuit diagram for each case.
Answer.
(i) Bulbs in parallel provide more illumination. This is because
(a) each bulb gets same voltage and is equal to the applied voltage.
(b) each bulb draws required current from the mains. Hence, they work properly.
(ii)When one bulb in each circuit get fused,
In series: Rest of the bulbs will not glow. This is because in series arrangement, there is only a single path for the flow of current.
In parallel: Rest of the bulbs will continue to glow as in parallel connection,
(a) individual branch in the circuit completes its own circuit, or
(b) different paths are available for the flow of current.
(iii) Circuit diagram

28. (a) Though same current flows through the electric line wires and the filament of bulb, yet only the filament glows. Why?
(b) The temperature of the filament of bulb is 2700°C when it glows. Why does it not get burnt up at such high temperature?
(c) The filament of an electric lamp, which draws a current of 0.25 A is
used for four hours. Calculate the amount of charge flowing through the
circuit.
(d) An electric iron is rated 2 kW at 220 V. Calculate the capacity of the fuse
that should be used for the electric iron.
Answer. (a) Electric line wires offer extremely low resistance to the flow of current, so
they do not glow because negligible heat is produced in it.
The filament of bulb glows because it becomes red hot due to large amount of
heat produced, as it offers high resistance to the flow of current through it.
(b) The filament of bulb when it glows at 2700°C does not get burnt because the tungsten metal of filament has
(i) a very high melting point (of 3380°C) and
(ii) a high resistivity.

(c) Given: I = 0.25 A, t = 4 h = 4 x 60 x 60 sec.
So, amount of charge flowing the filament of electric lamp
So, the capacity of the fuse that should be used for the electric iron is of the order of 10 A.

29.

In the given circuit, connect a nichrome wire of length ‘L’ between points X and Y and note the ammeter reading.
(i) When this experiment is repeated by inserting another nichrome wire of the same thickness but twice the length (2L), what changes are observed in the ammeter reading?
(ii) State the changes that are observed in the ammeter reading if we double the area of cross-section without changing the length in the above experiment. Justify your answer in both the cases.
(b) “Potential difference between points A and B in an electric field is 1 V”. Explain the above statement.

Answer. (a)(i) Ammeter reading in the second case is half of the ammeter reading
in first case. This is because
=> i.e. when length is doubled, the resistance is doubled, this means the current is halved.
(ii) On doubling the area of cross-section without changing the length of the conductor, twice of the previous reading is observed in the ammeter. This is because
So, when A is double, resistance becomes half, current will be doubled. (b) “Potential difference between points A and B in an electric field is 1 V”. It means 1 J work is done in moving 1 C of charge from point B to point A in an electric field.

Very Short Answer Type Questions [1 Mark] – Year 2011

30. How is an ammeter connected in a circuit to measure current flowing through it?
Answer. In series

31. What happens to resistance of a conductor when its area of cross-section is increased?
Answer.

32. A given length of a wire is doubled on itself and this process is repeated once again. By what factor does the resistance of the wire change?
Answer. Am. Length becomes one-fourth of the original length and area of cross-section becomes four times that of original.

So, new resistance is (1/16)th of original resistance.

Short Answer Type Questions[l] [2 Marks] – Year 2011

33.A 9Ω resistance is cut into three equal parts and connected in parallel. Find the equivalent resistance of the combination.
Answer.

34.An electric iron has a rating of 750 W, 220 V. Calculate the (i) current flowing through it, and (ii) its resistance when in use.
Answer.

35.(a) What do the following circuit symbols represent?

(b) The potential difference between the terminals of an electric heater is 60 V when it draws a current of 4 A from the source. Find the resistance of heater when in use.
Answer.
(a) (i) Wires crossing without touching each other.
(ii) Rheostat/Variable resistor
(b) Given: V = 60 V, I = 4 A, R = ?
From Ohm’s law, V = IR
60 = 4 x R = 15 Ω

36.The charge possessed by an electron is 1.6 X 10-19 coulombs. Find the number of electrons that will flow per second to constitute a current of 1 ampere.
Answer.

37.Explain the role of fuse in series with any electrical appliance in an electric circuit. Why should a fuse with defined rating for an electric circuit not be replaced by one with a larger rating?
Answer. Fuse wire is a safety device connected in series with the live wire of circuit. It has high resistivity and low melting point. It melts when a sudden urge of large current passes through it and disconnects the entire circuit from the electrical supply. But, in case if we use a larger rating instead of a defined rating, then it will not protect the circuit as high current will easily pass through it and it will not melt.

38.The wattage of a bulb is 24 W when it is connected to a 12 V battery. Calculate its effective wattage if it operates on a 6 V battery (Neglect the change in resistance due to unequal heating of the filament in the two cases).
Answer.

39.Consider the following circuit diagram. If R₁ = R₂ =R₃ = R₄= R₅ = 3 Ω, find the equivalent resistance(R_s) of the circuit.

Answer.

Short Answer Type Questions[ll] [3 Marks] – Year 2011

40. A torch bulb is rated 2.5 V and 750 mA. Calculate (i) its power, (ii) its resistance and (iii) the energy consumed, if this bulb is lighted for four hours.
Answer.

41.Series arrangements are not used for domestic circuits. List any three reasons.
Answer. Series arrangements are not used for domestic circuit because

1.  The electrical appliances need current of widely different values to operate properly.
2. In series arrangement, when one component fails, the circuit is broken and none of the components works.
3. All electrical appliances work at a constant voltage. But in series circuit, the current is constant throughout the electric circuit and potential is different across the different components. So, series arrangement is not suitable for domestic circuits.

42.Name the physical quantity which is (i) same (ii) different in all the bulbs
when three bulbs of:
(a) same wattage are connected in series.
(b) same wattage are connected in parallel.
(c) different wattage are connected in series.
(d) different wattage are connected in parallel.
Answer. (a) For identical bulbs in series- same current, same potential difference.
(b) For identical bulbs in parallel- same potential difference, different current.
(c) For unidentical bulbs in series- same current, different potential difference.
(d) For unidentical bulbs in parallel- different current, same potential difference.

43. Two devices of rating 44 W, 220 V and 11 W, 220 V are connected in series. The combination is connected across a 440 V mains. The fuse of which of the two devices is likely to burn when the switch is ON? Justify your answer.
Answer.

44.Five resistors are connected in a circuit as shown. Find the ammeter reading when circuit is closed.

Answer.

45.Study the circuit shown in which three identical bulbs B₁, B₂ and B₃ are connected in parallel with a battery of 4.5 V.
(i) What will happen to the glow of other two bulbs if the bulb B₃ gets fused?
(ii) If the wattage of each bulb is 1.5 W, how much reading will the ammeter A show when all the three bulbs glow simultaneously?
(iii) Find the total resistance of the circuit.

Answer.
(i) The glow of other two bulbs remains the same.
(ii)In parallel combination, potential difference across each resistance will remain same.

So, potential across each bulb = 4.5 V

Wattage of each bulb = 1.5 W
Therefore, when all the three bulbs glow simultaneously, the ammeter A shows 1 A reading.
(iii) Potential difference across each bulb = 4.5 V Wattage of each bulb = 1.5 W
.’. Resistance of

46.A circuit is shown in the diagram given below.
(a) Find the value of R.
(b) Find the reading of the ammeter.
(c) Find the potential difference across the terminals of the battery.

Answer.
(a) Potential difference across 6Ω = 12 V
.’. Current through 6 Ω,

47.Consider the circuit shown in the diagram. Find the current in 3Ω resistor.
Answer.

48.Study the I-V graph for four conductors A, B, C and D having resistance R_A,R_B, R_c and R_D respectively, and answer the following questions:

(i) Which one of these is the best conductor?
(ii) f all the conductors are of same length and same material, which is the thickest?
(iii)If all the conductors are of same thickness and of same material, which is the longest?
(iv)If the dimensions of all the conductors are identical, but
their materials are different which one would you use as (a) resistance wire (b) connecting wire?
(v) Which one of the following relations is true for these conductors?

(vi) If conductors A and B are connected in series and I-F graph is plotted for the combination, its slope would be
(a) less than that of A. (b) more than that of A.
(c) between A and B. (d) more than that of D.
(vii)If conductors C and D are connected in parallel and I-V graph is plotted for the combination, its slope would be
(a) lesser than that of A. (b) more than that of D.
(c) between C and D. (d) between B and C.
Answer.

(iii)Resistance oC length. So, A is the longest.
(iv)(a) Resistance wire – A (b) Connecting wire – D
(v) Option (a) is correct.
(vi)(a) In series, resistances are added. (Rs =R_A + R_B). So, in the given I-V
graph, slope of series combination would be less than that of A.
(vii)(b) In parallel combination, the equivalent resistance is less than the least
value resistance in the circuit. So, in the given I-V graph, slope for parallel combination is more than that of D

Short Answer Type Question[l] [2 Marks] – Year 2010

49. In an experiment to study the relation between the potential difference across a resistor and the current through it, a student recorded the following observations:

On examine the above observations, the teacher asked the student to reject one set of readings as the values were out of agreement with the rest. Which one of the above sets of readings can be rejected? Calculate the mean value of resistance of the resistor based on the remaining four sets of readings.
Answer. The third reading for V = 3.0 volt and I — 0.6 A will be rejected as it has larger deviation from the rest of the readings.
The value of resistance in the other four observations will be I (using R = V/I) 10Ω, 11 Ω, 10 Ω and 10.67 Ω.
So, the mean value of resistance = 41.67/4 = 10.417 = 10.42 Ω

Long Answer Type Questions [5 Marks] – Year 2010

50. Explain with the help of a labelled circuit diagram, how will you find the resistance of a combination of three resistors, of resistance R₁, R₂ and R₃ joined in parallel. Also mention how will you connect the ammeter and the voltmeter in the circuit while measuring the current in the circuit and the potential difference across one of the three resistors of the combination.
Answer. Parallel Combination:

1.  Connect the three given resistor R₁, R₂ and R?i in parallel between the point XY with a battery, a plug key and ammeter in series as shown in figure.
   
2. Connect voltmeter in parallel with these resistors between the terminals X and Y.
3. Close the key and note the ammeter and voltmeter reading. Ammeter shows the total current drawn by the parallel combination of these resistors while voltmeter shows the voltage applied across the combination.
4. Using Ohm’s law, find the equivalent resistance of the combination, i.e. equivalent resistance,
   

To find the current flow through any one of the resistor, ammeter will be connected in series with that resistor and to measure the potential difference across that resistor, voltmeter must be connected in parallel with that resistor as shown.

51. Derive the expression for the heat produced due to a current T flowing for a time interval ‘£’ through a resistor ‘R’ having a potential difference ‘V’ across its ends. With which name is the relation known? How much heat will an instrument of 12 W produce in one minute if it is connected to a battery of 12 V?
Answer. Heat produced in a conductor: Consider a wire AB having a resistance ‘R’ connected across the terminals of a cell. Let V be the potential difference applied by cell across the ends of a wire.

Let W be the work done in carrying the charge q across the conductor, then

52.Deduce the expression for the equivalent resistance of the parallel combination of three resistors R₁, R₂ and R₃
Consider the following electric circuit:

(a) Which two resistors are connected in series?
(b) Which two resistors are connected in parallel?
(c) If every resistor of the circuit is of 2 Ω, what current will flow in the circuit?
Answer. Consider the following parallel circuit shown below: Let I₁, I₂ and I₃ be the current flow through the resistor R₁, R₂ and R₃ connected in parallel.
Using Ohm’s law, current through each resistor is

Very Short Answer Type Questions [1 Mark] – Year 2009

53. Two resistors of 10 Ω and 15 Ω are connected in series to a battery of 6 V. How can the values of current passing through them be compared?
Answer. In series, same current flows through each resistor. So, ratio of current is 1 : 1.

54, A wire of resistance 20 Ω is bent to form a closed square. What is the resistance across a diagonal of the square?
Answer.

Short Answer Type Questions[l] [2 Marks] – Year 2009

55.Draw a schematic diagram of an electric circuit consisting of a battery of five 2 V cells, a 20 Ω resistor, a 30 Ω resistor, a plug key, all connected in series. Calculate the value of current flowing through the 20 Ω resistor and the power consumed by the 30 Ωresistor.
Answer. Req = 20 + 30 = 50 Ω

Current through both 20 Ωand 30 Ω= I =10/50
= 0.2 A
Power consumed by 30 Ω = I2R = (0.2)2 x 30=1.2W

56. A piece of wire of resistance 20 Ω is drawn out so that its length is increased to twice its original length. Calculate the resistance of the wire in the new Situation.
Answer.

57. What is an electric circuit? Distinguish between an open and a closed circuit.
Answer. An arrangement for maintaining the continuous flow of electric current by the electrical energy source through the various electrical components connected with each other by conducting wires is termed as electric circuit.
An open circuit does not carry any current, while a closed circuit carries current.

Short Answer Type Questions[ll] [3 Marks] – Year 2009

58. Two resistors with resistances 5Ω and 10 Ω are to be connected to a battery of emf 6 V so as to obtain:
(i) minimum current
(ii) maximum current
(a) How will you connect the resistances in each case ?
(b) Calculate the strength of the total current in the circuit in the two cases.
Answer.
(a) As current is inversely proportional to resistance for the same voltage. So, to get maximum current, the equivalent resistance has to be less. This means the resistors must be connected in parallel.
To get minimum current, the equivalent resistance has to be greater as

59.(a) Define the term ‘volt’.
(b) State the relation between work, charge and potential difference for an electric circuit.
Calculate the potential difference between the two terminals of a battery if 100 J of work is required to transfer 20 C of charge from one terminal of the battery to the other.
Answer.
(a) When 1 joule of work is done in carrying 1 coulomb of charge, from infinity to a point in the electric field, then potential at that point is called 1 volt.
(b) Potential difference, V = Work done on unit charge =W/q

Work is 100 J,q=20C
Potential difference,V=W/q=100/20=5V

60.(a) Define the term ‘coulomb’.
(b) State the relationship between the electric current, the charge moving through a conductor and the time of flow.
Calculate the charge passing through an electric bulb in 20 minutes if the value of current is 200 mA.
Answer.

(a) When 1 A current flows across the wire in 1 second, the charge transfer across its ends is said to be 1 coulomb.
(b) The relationship between the electric current I, the charge q and time t is

61.(a) How is the direction of electric current related to the direction of flow of electrons in a wire?
(b) Calculate the current in a circuit if 500 C of charge passes through it in 10 minutes.
Answer.
(a) Conventional direction of electric current is opposite to the direction of flow of electrons in a wire.
(b) q = 500 C, t = 10 X 60 = 600 s
I = 500/600 = 5/6A

Long Answer Type Question [5 Marks] – Year 2009

62.(a) Two resistors R₁and R₂ may form (i) a series combination or (ii) a parallel
combination, and the combination may be connected to a battery of 6 volts. In which combination, will the potential difference acrossR₁ and across R₂ be the same and in which combination, will the current through R₁ and through R₂ be the same?
(b) For the circuit shown in this diagram, calculate

(i) the resultant resistance.
(ii) the total current.
(iii) the voltage across 7 Ω resistor.
Answer. (a) Potential difference across R₁ and R₂ is same in parallel combination of R₁ and R₂ and the current through R₁ and R₂ will be same when they are connected in series.

Download Formula BookPhysics eBookChemistry eBookBiology eBook

The post Electricity Chapter Wise Important Questions Class 10 Science appeared first on Learn CBSE.

Magnetic  Effects of Electric Current Chapter Wise Important Questions Class 10 Science

Important QuestionsNCERT SolutionsSample PapersNCERT Exemplar Solutions

PREVIOUS YEARS’ QUESTIONS

Short Answer Type Questions [II] [3 Marks] – Year 2015

1.Describe an activity to show that the magnetic field lines produced when current is passed through the circular coil.
Answer.
Aim : To study the characteristics of magnetic field produced by a current carrying circular coil at its centre.
Apparatus Required : Rectangular cardboard having two holes, Thick copper circular coils of different radii having known number of turns, key, battery, rheostat, stand, iron filings.
Procedure :

1. Pass the coil through the two holes of cardboard in such a way that half of the loop is above the cardboard and remaining part should be below it and normal to the plane of cardboard.
2. Connect the circuit as shown.
   
3. Sprinkle iron filings uniformly on the cardboard.
4.  Allow the current to pass though the coil by inserting plug in the key.
5. Note the pattern of iron filings that emerges on the cardboard after tapping gently a few times. (Observation).
6. Place the compass at any point over the pattern of field. Observe the direction of needle. (Observation 2).

Observations :

1. (a) Iron filings are arranged in the form of concentric circles.
   (b) The concentric circles become larger and larger as we move away from the wire.
   (c) At the centre of loop, lines are almost straight and perpendicular to the plane of the loop.

Conclusion :

1. The concentric circles at every point of a current carrying circular loop represent the magnetic field around it.
2. Magnetic field line close to the axis of loop is straight and is perpendicular to the plane of the coil.
3. Field lines keep on diverging as we move away from the centre of loop.

2. What is meant by solenoid? How does a current carrying solenoid behave? Give its main use.
Answer. Solenoid: A coil of many circular turns of insulated copper wire wound on a cylindrical insulating body (i.e., cardboard etc.) such that its length is greater than its diameter is called solenoid.

When current is flowing through the solenoid, the magnetic field line pattern resembles exactly with those of a bar magnet with the fixed polarity,
i.e. North and South pole at its ends and it acquires the directive and attractive properties similar to bar magnet. Hence, the current carrying solenoid behave as a bar magnet.
Use of current carrying solenoid: It is used to form a temporary magnet called electromagnet as well as permanent magnet.

3.For the current carrying solenoid as shown below, draw magnetic field lines and giving reason explain that out of the three points A, B and C at which point the field strength is maximum and at which point it is minimum.

Answer. Outside the solenoid magnetic field is minimum. At the ends of solenoid, magnetic field strength is half to that inside it. So Minimum – at point B; Maximum – at point A

4. With the help of a diagram of experimental setup describe an activity to show that the force acting on a current carrying conductor placed in a magnetic field increases with increase in field strength.
Answer.
Aim : To show that force acting on a current carrying conductor placed in a magnetic field increases with the field strength.
Apparatus Required : Aluminium rod, stand horse shoe magnet of different intensity, cell, key and connecting wires.
Procedure :

1. .Arrange the set-up as shown in figure.
   
   2.Plug the key, the current flowing through the rod from Q to P observe the displacement of rod.
   3.Now unplug the key and remove the first horse shoe magnet and place the second horse shoe magnet of higher magnetic field strength in a similar manner to that of first.
   4.Plug the key, the current again flow through the rod from Q to P. Again observe the deflection of rod.
   5.Now bring both’the magnet closer together (to ensure greater magnetic field than that of previous case). Again observe the motion of rod.

Observations : Each time, the conductor moves faster than that of previous one. It is possible only when conductor gets accelerated more each time which required more force. (F = ma)
Thus, if the magnetic field strength is increased, the rod will experience a greater force and move faster.
Conclusion : The force acting on a current carrying conductor placed in a magnetic field increases with increase in field strength.

5.What are magnetic field lines? Justify the following statements
(a) Two magnetic field lines never intersect each other.
(b) Magnetic field lines are closed curves.
Answer.
Magnetic field lines: It is defined as the path along which the unit North pole (imaginary) tends to move in a magnetic field if free to do so.
(a) The magnetic lines of force do not intersect (or cross) one another. If they do so then at the point of intersection, two tangents can be drawn at that point which indicates that there will be two different directions of the same magnetic which field, i.e. the compass needle points in two different directions which is not possible.
(b) Magnetic field lines are closed continuous curves. They diverge from the north pole of a bar magnet and converge its south pole. Inside the magnet they move from south pole to north pole.

Long Answer Type Question [5 Marks] – Year 2015

6.(a) Describe activity with labelled diagram to show that a current carrying
conductor experience a force in a magnetic field.
(b) State the rule to determine the direction of force.
Answer.
(a) Without using a magnet, magnetic field can be produced by flowing the current through a straight conductor or a solenoid.
Aim : To show that magnetic field exerts a force on a current carrying conductor.
Apparatus required : Aluminium rod, stand, strong horse shoe magnet, cell, key and connecting wires.

Procedure :

1. Hang the aluminium rod with the help of clamp stand such that it passes between the North and South pole of the magnet with the magnetic field directed upwards and the rod being horizontal and perpendicular to the field.
2. Connect the aluminium rod in series with a battery, a key as shown in figure.
3. Plug the key, the current flows through the rod from Q to P and observe the direction of motion of the rod.
4. Reverse the direction of current by reversing the battery connection. Again observe the direction of displacement of aluminium rod.
5. Restore the original direction of current and change the direction of field vertically downwards by interchanging the two poles of the magnet. Observe the deflection of rod again.
6. Place the wire parallel to magnetic field and allow the current to pass through it. Check the deflection of rod again.

Observation :

1. On plugging the key in step 3, the aluminium rod moves towards left.
2. In step 4, rod displaces towards right.
3. In step 5, rod moves towards right again.
4. In step 6, rod does not move in any direction.

Conclusion :

1. Magnetic field exerts a force on a current carrying conductor.
2. The force exerted on the current carrying conductor depends upon the direction of current and direction of magnetic field acting on it.
3. Displacement of the rod or the magnetic force on it is largest when the direction of current is at right angle to the direction of magnetic field.
4.  When current carrying conductor is placed parallel to the magnetic field, it experiences no force.
   (b) Direction of force experienced by a current carrying straight conductor placed in a magnetic field which is perpendicular to it is given by Fleming’s left hand rule.
   Stretch the thumb, forefinger and middle finger of left hand in such a way that they are mutually perpendicular to each other. If the forefinger points in the direction of magnetic field and the middle finger in the direction of current, then the thumb will point in the direction of motion or the force acting on the conductor.

Short Answer Type Questions [I] [2 Marks] – Year 2014

7.Why and when does a current carrying conductor kept in a magnetic field experience force? List the factors on which direction of this force depends?
Answer. The drifting of free electrons of a conductor in a definite direction causes the current to flow through it. When such conductor is placed in a uniform magnetic field, each drifted electron of a conductor experience a magnetic force. This force is collectively experience by a conductor as a whole. Hence a current carrying conductor kept in a magnetic field experience a force. The direction of magnetic force depends on
(i) direction of current through the conductor, and
(ii) direction of magnetic field.

8.How is the strength of magnetic field near a straight current-conductor
(i) related to the strength of current in the conductor?
(ii) is affected by changing the direction of flow of current in the conductor?
Answer.
(i) The strength of magnetic field around a straight current conductor increases
on increasing the strength of current in the conductor or vice versa.
(ii)The direction of magnetic field around a straight current carrying conductor gets reversed if the direction of current through that conductor is reversed.

9.What is meant by the term ‘frequency of an alternating current’? What is its value in India? Why is an alternating current considered to be advantageous over direct current for long range transmission of electric energy?
Answer.

•  Frequency of Alternating current is equal to the number of cycles completed in one second.
•  In India, frequency of AC is 50 Hz i.e. 50 cycles per second.
•  An alternating current is considered to be advantageous over direct current for long range transmission of electric energy because it can be transmitted over long distances to distant places without much loss of electric power as compared to direct current.

Short Answer Type Questions [II] [3 Marks] – Year 2014

10. State one main difference between A.C and D.C. Why A.C is preferred over D.C for long range transmission of electric power? Name one source each of D.C and A.C. 
Answer. Difference between A.C. and D.C. The alternating current (A.C.) reverses its direction periodically whereas the direct current (D.C.) always flows in one direction.
A.C. is preferred over D.C. because it can be transmitted over long distance without much loss of energy.
D.C. source : Battery A.C. source : A.C. generator

11. State the consequences that can lead to a short circuit.Or
One of the major cause of fire in office building is short circuiting. List three factors which may lead to the short circuit.
Answer. It occurs as a consequence of

•  failure of electrical insulation’s due to which live wire comes in direct contact with neutral or earth wire.
•  presence of external conducting material such as water which is introduced accidentally into the circuit.
• electrical appliances are forced to operate when its moving parts are jammed.
•  connection of current carrying parts of electrical equipment’s comes in contact to one another due to human or natural cause and
•  use of less rating wires.
  When this happens, there is an excessive electric current which can damage the circuit and may also cause electrical fires.

Long Answer Type Questions [5 Marks] – Year 2014

12.(a) Describe an activity to demonstrate the pattern of magnetic field lines around a straight conductor carrying current.
(b) State the rule to find the direction of magnetic field associated with a current carrying conductor.
(c) What is the shape of a current carrying conductor whose magnetic field
pattern resembles that of a bar-magnet ?
Answer.
(a) Aim : To study the magnetic field due to a straight current carrying conductor.
Apparatus Required : A thick conducting wire, battery, rheostat, magnetic needle, ammeter (0-5 A), key, a cardboard, a stand to hold the wire, iron filings and sprinkler of iron filings.
Procedure :

1. Attach the thick wire through a hole at the middle of the cardboard and clamp it in a stand.
2. Attach the ends of the wire through a key, variable resistor and an ammeter on either side of a battery and hold it vertically and perpendicularly to the board.
3. Spread the iron filings uniformly on the cardboard and place the magnetic needle on the board.
4. Close the key and tap the cardboard slightly and observe the orientation of iron filings.
   

Observation :

1. Just on closing the key, the iron filings are aligned in the pattern of concentric circles around the wire.

Conclusion :

1. Current carrying conductor is a source of magnetic field.
2. The magnetic field is in the form of concentric circles whose centre lies on the wire.
   (b) Right-Hand Thumb Rule. This rule is used to find the direction of magnetic field due to a straight current carrying wire.
   
   It states that if we hold the current carrying-conductor in the right hand in such a way that the thumb is stretched along the direction of current, then the curly finger around the conductor represent the direction of magnetic field produced by it. This is known as right-hand thumb rule.
   Direction of Field Lines due to current carrying straight conductor is as shown in figure.
   (c) Solenoid.

13.(a) Explain why there are two separate circuits one for high power rating appliances and other for low power rating appliances.
(b) A domestic circuit has 5A fuse. How many bulbs of rating 100W, 220V can be safely used in this circuit? Justify your answer.
Answer.
(a) Two separate circuits are formed in the domestic wiring, one for high power rating appliances called power circuit and other for low power rating called lightning circuit.
Power circuit: The circuit which draw heavy current (15 A) from mains and used for high power rating devices such as microwave, oven, air conditioners, geysers, washing machine, etc., is known as power circuit. Lightning circuit: The circuit which draw small amount of current from the mains and used for low power rating devices such as bulb, tube light, fans, T.V., Computer, etc. having a current rating of 5 A is known as lightning circuit.

14.(i) Design an activity with the help of two nails, very thin aluminium strip, a 12 V Battery and a key to illustrates.
(ii) Cable of a microwave oven has three wires inside it which have insulation of different colours black, green and red. Mention the significance of the three colours and potential difference between red and black one.
Answer.
(a) Aim: How electric fuse works?
Apparatus required : Two nails, card board, very thin aluminium strip, a 12 V battery, key and connecting wires.
Procedure:

1.  Insert the two nails vertically on the card board.
2.  Take very thin aluminium strip and tie it between the nails.
3. Make a circuit as shown in figure with 12 V battery and key with the help of connecting wires.
   
4.  If there are any fans running in the room, switch them off.
5.  Now switch on the current in the circuit by pressing the key or by moving the switch of the ‘ON’ position.
6.  Now pass the current through the circuit for some time. Observe the strand of aluminium strip between the two nails carefully.
   Observation: The strand of aluminum strip melt and break quickly on passing the large electric current through it.

Conclusion: When current flows through the circuit, exceed the rating of aluminium strip, i.e. safe limit, its temperature increases. This make it overheated. As a result, aluminium strip melts and breaks the circuit. Hence, very thin aluminium strip between the two nails acts as a fuse wire. This activity shows that how fuse works.
(b) Significance of insulation colour:

1.  Red colour insulation wire – Live wire
2. Black colour insulation wire – Neutral wire
3.  Green colour insulation wire – Earth wire

Live wire is at higher potential of 220 V while neutral wire is at zero potential. So, potential difference between red and black insulation wire is 220 V.

Short Answer Type Questions [I] [2 Marks] – Year 2013

15.Explain any two situations that can cause electrical hazards in domestic circuits.
Answer. (i) Connecting too many electrical devices to a single socket or in the extension
cord for any length of time draws high current from the mains that will exceed the current rating of connecting wires. The wires cannot withstand such a high current and melt and may cause fire.
(ii) Most electrical hazards in domestic circuits are caused by the faulty electrical outlets, old and out-dated appliances. The chances of short circuit i.e., contact of live wire and neutral wires with each other due to damage in their insulation or some fault in the appliances are very high. It may result spark at the contact point which may even cause fire,

16.List in tabular form two major differences between an electric motor and a
generator.
Answer.

Long Answer Type Question [5 Marks] – Year 2013

17. Two coils C₁ and C₂are wrapped around a non conducting cylinder. Coil  C₁is connected to a battery and key and C₂ with galvanometer G. On pressing the key (K), current starts flowing in the coil  C₁State your observation in the galvanometer:

(i) When key K is pressed on
(ii) When current in the coil C₁ is switched off.
(iii) When the current is passed continuously through coil  C₁
(iv) Name and state the phenomenon responsible for the above observation. Write the name of the rule that is used to determine the direction of current produced in the phenomena.
Answer.
(i) When key is pressed on, the galvanometer needle deflects momentarily in one direction.
(ii) When the current in the coil  C₁ is switched off, the galvanometer needle deflects again momentarily but in opposite direction to that in the previous case.
(iii) When current is passed continuously through coil  C₁ , no deflection is observed in the galvanometer.
(iv) The phenomenon responsible for the above observations is electromagnetic induction.
Electromagnetic Induction: The process, by which a changing magnetic field in a conductor induces a current in another conductor placed nearby, is called electromagnetic induction.
• Fleming’s right hand rule is used to determine the direction of current produced in the phenomena of electroynagnetic induction.

Very Short Answer Type Questions [1 Mark] – Year 2012

18. Name the type of current:
(a) used in household supply. (b) given by a cell.
Answer.
(a) Alternating current. (b) Direct current.

19. State the direction of magnetic field in the following case.

Answer. Perpendicular to the plane of paper in the outward direction by using Fleming’s left hand rule.

20. Give one application of electromagnetic induction.
Answer. This phenomenon is used in electric generator.

21. Name the physical quantities which are indicated by the direction of thumb and forefinger in the Fleming’s right hand rule?
Answer. In Fleming’s right hand rule,
thumb indicates — direction of motion of the conductor; forefinger indicates — direction of magnetic field.

22. A positively charged particle (alpha-particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is
(a) towards north (b) towards east
(c) downward (d) upward
Answer. (d) Upward (Apply Fleming’s left hand rule).

Short Answer Type Questions[l] [2 Marks] – Year 2012

23. The given magnet is divided into three parts A, B, and C.

Name the parts where the strength of the magnetic field is: (i) maximum (ii) minimum.
How will the density of magnetic field lines differ at these parts?
Answer.
(i) Maximum strength – at A and C
(ii) Minimum strength – at B
At A and C, magnetic field lines are crowded while at B, they are spread out.

24. A compass needle is placed near a current-carrying wire. State your observation for the following cases, and give reason for the same in each case.
(a) Magnitude of electric current in the wire is increased.
(b) The compass needle is displaced away from the wire.
Answer.
(a) Observation: The deflection of the needle increases.
Reason: Magnetic field strength due to current-carrying wire increases as current in the wire increases,
(b) Observation: The deflection in the compass needle decreases as its displacement from the current-carrying wire increases.
Reason: The strength of magnetic field reduces with the increase in distance
from the wire as

25. (a) Two magnets are lying side by side as shown below.
Draw magnetic field line between poles P and Q.

(b) What does the degree of closeness of magnetic field lines near the poles signify?
Answer.

(b) The degree of closeness of magnetic field lines near the poles signify that the field is stronger there, i.e. the pole of another magnet when placed in the magnetic field experiences a greater force where the field lines are crowded.

26. Magnetic field lines of two magnets are shown in fig. A and fig. B.

Select the figure that represents the correct pattern of field lines. Give reasons for your answer. Also name the poles of the magnets facing each other.
Answer. Figure B represents the correct pattern of field lines. In figure A, field lines cross each other which is not possible because if they cross each other, at the point of intersection, there would be two directions of field lines.
In figure B, field lines are emerging in nature, so poles of magnet facing each other are north poles while opposite faces will have south polarity.

Short Answer Type Questions[ll] [3 Marks] – Year 2012

27. What is short circuiting? State one factor/condition that can lead to it. Name a device in the household that acts as a safety measure for it. State the principle of its working.
Answer. Short circuiting: When electric circuit offers very low resistance to the flow of current through it, the current increases heavily and the circuit is said to be short circuited. It occurs when live wire touches the neutral wire. This happens due to the damage in insulation of the power lines.
Safety measure device: Fuse.
Working principle of fuse: It works on the heating effect of electric current or Joule’s law of heating. According to this law, the heat produced in a resistor is directly proportional to the
(i) square of current for a given resistance.
(ii) resistance for a given current and
(iii) time for which the current flows through the resistor.
H = I2Rt
So, when current in the circuit increases, the wire with low melting point in it melts to the heat generated. Hence, the circuit breaks and electrical devices and appliances are saved. _

28. Write one application of each of the following:
(a) Right-hand thumb rule (b) Fleming’s left hand rule
(c) Fleming’s right hand rule
Answer.
(a) Right-hand thumb rule is used to find the direction of magnetic field in a coil of wire and the electric current in a straight conductor.
(b) Fleming’s left hand rule is used to find the direction of force exerted on a current-carrying conductor placed in a magnetic field as in electric motor.
(c) Fleming’s right hand rule is used to find the direction of induced current in a closed circuit placed in changing magnetic field as in electric generator.

29. State one main difference between A.C. and D.C. Why is A.C. preferred over D.C. for long range transmission of electric power? Name one source each of D.C. and A.C.
Answer. Difference between A.C. and D.C.: The alternating current (A.C.) reverses its direction periodically whereas the direct current (D.C.) always flows in one direction.
A.C. is preferred over D.C. because it can be transmitted over long distance without much loss of energy.
D.C. source: Battery A.C. source: A.C. generator

Long Answer Type Questions [5 Marks] – Year 2012

30.Two coils of insulated copper wire are wound over a non -conducting cylinder as shown. Coil I has larger number of turns.
(i) Write your observations when,
(a) key K is closed,
(b) key K is opened.

(ii)When the current is passed continuously through coil I.
Give reason for your observations.
(iii)Name and state the phenomenon responsible for the above observation.
(iv) Write the name of the rule that is used to determine the direction of current produced in the phenomenon.
(v) Name the two coils used in this experiment.
Answer.
(i) (a) When key is closed, the galvanometer needle deflects momentarily in one direction. ,
Reason: When key is closed, magnetic field lines around coil 2 increases momentarily. This causes an induced current to flow through it and hence deflection occurs in one direction.
(b) When key is opened, the galvanometer needle deflects again momentarily but in opposite direction.
Reason: When key is open, magnetic field lines around coil 2 decreases momentarily. This causes an induced current to flow in opposite direction. Hence, deflection occurs in opposite direction.
(ii) When current is passed continuously through coil I, no deflection is observed in the galvanometer.
Reason: There will be no change in magnetic field lines passing through the coil 2. Hence, no induced current will be set up in coil 2.
(iii) The phenomenon observed in above cases is electromagnetic induction. It is a process by which a changing magnetic field in a conductor induces a current in another conductor placed nearby.
(iv) Fleming’s right hand rule
(v) Coil I – Primary coil Coil II – Secondary coil

31.(a) Mention the effect of electric current on which the working of an electrical fuse is based.
(b) Draw a schematic labelled diagram of a domestic circuit which has a provision of a main fuse, meter, one light bulb and a socket.
(c) Explain the term overloading of an electric circuit.
Answer.
(a) Heating effect of electric current.
(b) Domestic circuit wiring consists of a main fuse, meter, one light bulb and a socket.

(c) The flow of large amount of current through the circuit beyond its bearing capacity due to use of many high power rating devices at the same time is called overloading.

32. Observe the figure given below and answer the following questions:
(a) Write the special name given to the coil AB which has many circular turns of insulated copper wire.

(b) State the nature of magnetic field inside AB when a current is passed through it.
(c) Redraw the diagram and sketch the pattern of magnetic field lines through and around AB.
(d) List two factors on which the strength of the magnetic field produced by AB depends.
(e) What is the effect of placing an iron core in the coil AB?
Answer.
(a) Solenoid.
(b) Uniform magnetic field.

(d) (i) Magnitude of current flowing through it.
(ii) Number of turns of a circular coil.
(e) It becomes an electromagnet.

Short Answer Type Questions[l] [2 Marks] – Year 2011

33. Insulation cover of which colour is conventionally used for earth wire? Why is an earth wire connected to metallic parts of appliances?
Answer. For earth wire, green or yellow colour insulation is used. The earth wire provides the low resistance conducting path for the current and maintains the potential of appliances body with that of the earth. So, earth wire is used as a safety measure.

34.Identify the poles of the magnet in the given figure (1) and (2).

Answer. Field lines emerge from north pole (N) and merge at the south pole (S) as shown in both the figures

35.Explain the role of fuse in series with any electrical appliance in an electric circuit. Why should a fuse with defined rating for an electric circuit not be replaced by one with a larger rating?
Answer. Fuse is a safety device connected in series with live wire or with any electrical appliance in an electric circuit. It stops the flow of unduly high electric current in the circuit by getting melted due to rise in temperature as per Joule’s law of heating.
High rating fuse wire has the larger capacity. So, it will not stop the flow of any relatively high current. Therefore, electrical devices cannot be protected from the possible damage.

36.The magnetic field associated with a current-carrying straight conductor is in anticlockwise direction. If the conductor was held along the east-west direction, what will be the direction of current through it? Name and state the rule applied to determine the direction of current.
Answer. Direction of current – east to west as determined by Right-hand thumb rule. Ri’-lu-Uand Thumb Rule: If we hold a current-carrying conductor by right hand in such a way that the stretched thumb is along the direction of current, then the curly fingers around the conductor represents the direction of field lines of magnetic field.

37. Two circular coils A and B are placed close to each other. If the current in the coil A is changed, will some current be induced in the coil B? Give reason.
Answer. Yes, when a current in coil A changes, magnetic field lines linked with coil B also change. Hence, due to change in number of magnetic field lines, there is an induced current in coil B. ,

Short Answer Type Questions[ll] [3 Marks] – Year 2011

38. How will the magnetic field produced at a point due to a current-carrying circular coil change if we:
(i) increase the current flowing through the coil?
(ii) reverse direction of current through the coil?
(iii) increase the number of turns in the coil?
Answer. Magnetic field (B) at the centre of the circular coil
(i) increases if the current is increased as
(ii) reverses on reversing the current. .
(iii) increases if the number of turns in the coil increases as field is directly
proportional to the number of turns.

39.(a) Mention the factors on which the direction of force experienced by a
current-carrying conductor placed in a magnetic field depend.
(b) Under what condition is the force experienced by a current-carrying conductor placed in a magnetic field maximum?
(c) A proton beam is moving along the direction of a magnetic field. What force is acting on proton beam?
Answer. (a) The direction of force experienced by the current-carrying conductor depends on:
(i) direction of current and
(ii)direction of magnetic field.
(b) When the direction of current is at right angle to the direction of magnetic field, the force is maximum.
(c) No force is experienced by the proton beam. As proton beam is moving along the direction of magnetic field.

40. A coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is (a) pushed into the coil,
(b) withdrawn from inside the coil,
(c) held stationary inside the coil?
Answer.
(a) When a bar magnet is pushed into the coil, magnetic field lines linked with
the coil changes (increases). It causes the electric current to get induced in it. The needle of galvanometer will move momentarily in one direction.
(b) When a bar magnet is withdrawn from inside the coil, the magnetic field lines linked with the coil changes but in decreasing order. Current will be induced in the coil which will be indicated by deflection of needle in the galvanometer. The deflection is opposite to that in case (a). This indicates that the direction of induced current is now opposite to the direction of induced current in case (a).
(c) When bar magnet is held stationary inside the coil, there is no deflection in the galvanometer. This is because there is no change in magnetic field lines linked with the coil. Hence, no induced current will flow through the coil.

41. State the rule to determine the direction of a
(a) magnetic field produced around a straight conductor carrying current,
(b) force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it.
Answer.
(a) Direction of magnetic field produced around a straight current-carrying conductor is given by right-hand thumb rule.
If we hold a current-carrying conductor in a right hand in such a way that the stretched thumb is along the direction of current, then the curly fingers around the conductor represent the direction of magnetic field lines.
(b) Direction of force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it, is given by Fleming’s left hand rule.
Stretch the thumb, forefinger and middle finger of left hand in such a way that they are mutually perpendicular to each other. If the forefinger points to the direction of magnetic field and the middle finger points to the direction of current, then the thumb will point to the direction of motion or the force acting on the conductor.

Long Answer Type Questions [5 Marks] – Year 2011

42.(a) Describe an activity to demonstrate the pattern of magnetic field lines around a straight conductor carrying current.
(b) State the rule to find the direction of magnetic field associated with a current-carrying conductor.
(c) What is the shape of a current-carrying conductor whose magnetic field pattern resembles that of a bar-magnet?
Answer. 
(a) Aim: To study the magnetic field due to a straight current-carrying conductor.
Apparatus Required: A thick conducting wire, battery, rheostat, magnetic needle, ammeter (0-5 A), key, a cardboard, a stand to hold the wire, iron filings and sprinkler of iron filings.
Procedure:

1. Attach the thick wire through a hole at the middle of the cardboard and clamp it in a stand.
2. Attach the ends of the wire through a key, variable resistor and an ammeter. on either side of a battery and hold it vertically and perpendicularly to the board.
3. Spread the iron filings uniformly on the cardboard and place the magnetic needle on the board.
4. Close the key and tap the cardboard slightly and observe the orientation of iron filings.
   

 Observation: Just on closing the key, the iron filings are aligned in the pattern of concentric circles around the wire.

Conclusion:

1.  A current-carrying conductor is a source of magnetic field.
2.  The magnetic field is in the form of concentric circles whose centre lies on the wire.
   (b)Right – Hand thumb Rule: Hold the current-Carrying wire in your right hand, such that the thumb indicates the direction of current, then the folded fingers will indicate the direction of magnetic field (lines) surrounding the wire.
   
   (c) Solenoid.

43.(a) Draw a diagram to represent a uniform magnetic field in a given region.
(b) List two properties of magnetic field lines.
Answer.
(a) Equidistant parallel line indicates a uniform magnetic field in a given region.

(b) Properties of magnetic field lines are:

1. The magnetic field lines of a magnet form continuous closed loops, i.e. outside the magnet, they emerge from north pole and merge at the south pole and inside the magnet, the direction of field lines is from its south pole to its north pole.
2. The degree of closeness of field lines indicates the strength of magnetic field.
3. Field lines never cross each other.

44.(i)With the help of an activity, explain the method of inducing electric current in a coil with a moving magnet. State the rule used to find the direction of electric current thus generated in the coil.
(ii) Two circular coils P and Q are kept close to each other, of which coil P carries a current. What will you observe in Q
(a) if current in the coil P is changed?
(b) if both the coils are moved in the same direction with the same speed? Give reason.
Answer.
(i) Take a coil AB of wire having a large number of turns.
Connect the ends of coil to a sensitive galvanometer as shown in figure.

Take a strong bar magnet and move its north pole towards the end ‘A’ of coil. The deflection in the needle of galvanometer indicates that the induced current flows in the circuit in anticlockwise direction. The end A of the coil behaves as a north pole.
When north pole of the magnet moves away from the coil, the deflection in the galvanometer occurs but in opposite direction.
Similar observations can be made when south pole of the magnet is moved towards the coil or away from it.
When magnet is kept at rest with respect to the coil, the deflection in the needle of galvanometer drops to zero.
Thus, the motion of a magnet, with respect to the coil, produces an induced potential difference which sets up an induced electric current in the circuit.
The direction of electric current thus generated in the coil can be found by using the Fleming’s right-hand rule.
(ii)Fleming’s right-hand rule: Stretch the thumb, forefinger and middle finger of right hand in such a way that they are mutually perpendicular to each other. If the forefinger indicates the direction of magnetic field and thumb shows the direction of motion of the conductor, then the middle finger will indicate the direction of induced current.
(a) If current in the coil P is changed, the magnetic field lines of forces linked with coil Q also change. So, induced potential difference is set up in the coil Q. This results in induced electric current in coil Q which opposes the change in current in coil P.
(b) If both the coils are moved in the same direction with the same speed, there will be no relative motion between them and hence, there will be no change in magnetic field lines of force associated with the secondary coil. Hence, no current will be induced in the coil.

Very Short Answer Type Question [1 Mark] – Year 2010

45. A charged particle enters at right angle into a uniform magnetic field as shown. What should be the nature of charge on the particle if it begins to move in a direction pointing vertically out of the page due to its interaction with the magnetic field?

Answer. Using Fleming’s left hand rule, the nature of charged particle is positive.

Short Answer Type Questions[l] [2 Marks] – Year 2010

46. A coil of insulated wire is connected to a galvanometer. What would be seen if a bar magnet with its north pole towards one face of the coil is
(i) moved quickly towards it,
(ii) moved quickly away from the coil and
(iii) placed near its one face?
Name the phenomenon involved.
Answer.
(i) Deflection in the galvanometer needle will be more on right-side.
(ii) Larger deflection in opposite direction as compared to the case (i) will be seen. (Hi) No deflection.
The phenomenon involved is electromagnetic induction.

47.Two coils A and B of insulated wires are kept close to each other. Coil A is connected to a galvanometer while coil B is connected to a battery through a key. What would happen if
(i) a current is passed through coil B by plugging the key, and (ii) the current is stopped by removing the plug from the key?
Explain your answer mentioning the name of the phenomenon involved.
Answer.In both the given cases, galvanometer shows momentary deflection but in opposite direction. In coil A, magnetic field lines [increased in case (i) and decreased in case (ii)] induce a potential difference across the coil A which sets up induced electric current in coil A. It is shown by the deflection in galvanometer. This is known as electromagnetic induction.

Very Short Answer Type Question [1 Mark] – Year 2010

48.Name any two appliances which are based on the application of heating effect of electric current.
Answer.Room heater and geyser.

Short Answer Type Questions[l] [2 Marks] – Year 2010

49.An electric oven of 2 kW power rating is operated in a domestic electric circuit (220.V) that has a current rating of 5 A. What result do you expect? Explain.

Answer. Current drawn by electric oven
Current rating of the circuit = 5 A
So, fuse will blow off and power supply will cut off

50.When is the force experienced by a current-carrying conductor placed in a magnetic field largest?
Answer. When the length of current-carrying conductor and direction of magnetic field are perpendicular to each other, the maximum force is experienced by the current-carrying conductor.

Long Answer Type Question [5 Marks] – Year 2010

51.Consider a circular loop of wire lying in the plane of the paper. Let the current
pass through the loop clockwise. With the help of a diagram, explain how the direction of the magnetic field can be determined inside and outside the loop. Name the law used to find the direction of magnetic field.
Answer. Consider a circular loop of wire of radius r with centre O lying in the plane of the paper. Let the current i pass through the loop clockwise. According to right hand thumb rule, direction of magnetic field due to any portion of small current carrying length of the coil is:
Direction of magnetic field inside the loop — Perpendicular to the plane of paper inwards.
Direction of magnetic field outside the loop — Perpendicular to the plane of paper outwards.

So, the direction of magnetic field can be considered as the direction of total magnetic field due to circular coil as current through all the elements will contribute to the magnetic field in the same direction.

Download Formula BookPhysics eBookChemistry eBookBiology eBook

The post Magnetic Effects of Electric Current Chapter Wise Important Questions Class 10 Science appeared first on Learn CBSE.