NCERT Solutions
Class 11 - Mathematics - Chapter 1: SETS
EXERCISE 1.2

Question. 1

Which of the following are examples of the null set?

(i) Set of odd natural numbers divisible by 2
(ii) Set of even prime numbers
(iii) { x : x is a natural number, x < 5 and x > 7 }
(iv) { y : y is a point common to any two parallel lines }

Answer:

(i), (iii), (iv)

Question. 2

Which of the following sets are finite or infinite?

(i) The set of months of a year
(ii) {1, 2, 3, ...}
(iii) {1, 2, 3, ... 99, 100}
(iv) The set of positive integers greater than 100
(v) The set of prime numbers less than 99

Answer:

(i) Finite (ii) Infinite (iii) Finite (iv) Infinite (v) Finite

Question. 3

State whether each of the following sets is finite or infinite:

(i) The set of lines which are parallel to the x-axis
(ii) The set of letters in the English alphabet
(iii) The set of numbers which are multiple of 5
(iv) The set of animals living on the earth
(v) The set of circles passing through the origin (0,0)

Answer:

(i) Infinite (ii) Finite (iii) Infinite (iv) Finite (v) Infinite

Question. 4

In the following, state whether A = B or not:

(i) A = {a, b, c, d}, B = {d, c, b, a}
(ii) A = {4, 8, 12, 16}, B = {8, 4, 16, 18}
(iii) A = {2, 4, 6, 8, 10}, B = {x : x is positive even integer and x ≤ 10}
(iv) A = {x : x is a multiple of 10}, B = {10, 15, 20, 25, 30, ...}

Answer:

(i) Yes (ii) No (iii) Yes (iv) No

Question. 5

Are the following pair of sets equal? Give reasons.

(i) A = {2, 3}, B = {x : x is solution of x² + 5x + 6 = 0}
(ii) A = {x : x is a letter in the word FOLLOW}, B = {y : y is a letter in the word WOLF}

Answer:

(i) No (ii) Yes

Question. 6

From the sets given below, select equal sets:

A = {2, 4, 8, 12}, B = {1, 2, 3, 4}, C = {4, 8, 12, 14}, D = {3, 1, 4, 2}
E = {−1, 1}, F = {0, a}, G = {1, −1}, H = {0, 1}

Answer:

B = D, E = G

NCERT Solutions Class 11 – Mathematics – Chapter 1: SETS – EXERCISE 1.2 | Detailed Answers