CBSE

Class –VIII Mathematics (Ex. 3.4) NCERT SOLUTION 1. State whether true or false: (a) All rectangles are squares. (b) All rhombuses are parallelograms. (c) All squares are rhombuses and also rectangles. (d) All squares are not parallelograms. (e) All kites are rhombuses. (f) All rhombuses are kites. (g) All parallelograms are trapeziums. (h) All squares … Read more

Exercise 14.1 1. Which of the following sentences are statements? Give reason for your answer. (i) There are 35 days in a month. (ii) Mathematics is difficult. (iii) The sum of 5 and 7 is greater than 10. (iv) The square of a number is an even number. (v) The sides of a quadrilateral have … Read more

Redox Reactions  1. Assign oxidation numbers to the underlined elements in each of the following species: (a) (b) (c) (d) (e) (f) (g) (h) 2. What are the oxidation numbers of the underlined elements in each of the following and how do you rationalise your results? (a) 3. Justify that the following reactions are redox … Read more

Exercise 1.3 1. Make correct statements by filling in the symbols or in the blank spaces: (i) {2, 3, 4} _______ {1, 2, 3, 4, 5} (ii) (iii) { is a student of class XI of your school} _______ { student of your school} (iv) { is a circle in the plane} _______ { is … Read more

Exercise 7.1 1. How many 3-digit numbers can be formed from the digits 1, 2, 3, 4 and 5 assuming that: (i) repetition of the digits is allowed (ii) repetition of the digits is not allowed. Ans. (i) The unit place can be filled by any one of the digits 1, 2, 3, 4 and … Read more

Exercise 10.2 In Exercises 1 to 8, find the equations of the line which satisfy the given conditions: 1. Write the equations for the and axis. Ans. Equation for axis is Equation for axis is 2. Passing through the point with slope Ans. Given: and 3. Passing through (0, 0) with slope Ans. Given: and … Read more

Exercise 1.5 1. Let U = {1, 2, 3, 4, 5, 6, 7, 8, 9}, A = {1, 2, 3, 4}, B = {2, 4, 6, 8} and C = {3, 4, 5, 6}. Find: (i) A’ (ii) B’ (iii) (A C)’ (iv) (A B)’ (v) (A’)’ (vi) (B – C)’ Ans. Given: U = … Read more

Exercise 7.2 1. Evaluate: (i) 8! (ii) (ii) 4! – 3! Ans. (i) 8! = = 40320 (ii) 4! – 3! = = 24 – 6 = 18 2. Is 3! + 4! = 7!? Ans. L.H.S. = 3! + 4! = = 6 + 24 = 30 R.H.S. = 7! = = 5040 L.H.S. … Read more

Exercise 10.3 1. Reduce the following equations into slope-intercept form and find their slopes and the intercepts. (i) (ii) (iii) Ans. (i) Given: ……….(i) Comparing with we have and (ii) Given: ……….(i) Comparing with we have and (iii) Given: ……….(i) Comparing with we have and 2. Reduce the following equations into intercept form and find … Read more

Exercise 3.1 1. Find the radian measures corresponding to the following degree measures: (i) (ii) (iii) (iv) Ans. (i) (ii) (iii) (iv) 2. Find the degree measures corresponding to the following radian measures . (i) (ii) (iii) (iv) Ans. (i) = (ii) = (iii) (iv) 3. A wheel makes 360 revolutions in one minute. Through … Read more

Exercise 7.3 1. How many 3-digit numbers can be formed by using the digits 1 to 9 if no digits is repeated? Ans. Total number of digits = 9 and Number of digits used without repetition = 3 Number of permutations = = = 504 2. How many 4-digit numbers are there with no digit … Read more

Miscellaneous Exercise 1. Find the values of K for which the line is: (a) parallel to the axis (b) parallel to the axis (c) passing through the origin. Ans. Given: Equation of line (a) If the line parallel to axis, then (b) If the line parallel to axis, then (c) If the line passes through … Read more

Exercise 3.2 Find the values of other trigonometric functions in exercises 1 to 5. 1. lies in third quadrant. Ans. Given: [ lies in third quadrant] Now, 2. lies in second quadrant. Ans. Given: [ lies in second quadrant] Now, 3. lies in third quadrant. Ans. Given: [ lies in third quadrant] Now, 4. lies … Read more