9th class Math, Chapter 3: Set and Functions MCQs

1. The set-builder form of the set {1, 1/3, 1/5, 1/7, …} is:

1. (A) {x | x = 1/n, n ∈ W}
2. (B) {x | x = 1/(2n + 1), n ∈ W} ✓
3. (C) {x | x = 1/(n + 1), n ∈ W}
4. (D) {x | x = 2n + 1, n ∈ W}

2. If A = { } then P(A) is:

1. (A) { }
2. (B) {1}
3. (C) {{ }} ✓
4. (D) ∅

3. If U = {1, 2, 3, 4, 5}, A = {1, 2, 3} and B = {3, 4, 5}, then U − (A ∩ B) is:

1. (A) {1, 2, 4, 5} ✓
2. (B) {2, 3}
3. (C) {1, 3, 4, 5}
4. (D) {1, 2, 3}

4. If A and B are overlapping sets, then n(A − B) is equal to:

1. (A) n(A)
2. (B) n(B)
3. (C) A ∩ B
4. (D) n(A) − n(A ∩ B) ✓

5. If A ⊆ B and B − A ≠ ∅, then n(B − A) is equal to:

1. (A) 0
2. (B) n(B)
3. (C) n(A)
4. (D) n(B) − n(A) ✓

6. If n(A ∪ B) = 50, n(A) = 30 and n(B) = 35, then n(A ∩ B) =

1. (A) 23
2. (B) 15 ✓
3. (C) 9
4. (D) 40

7. If A = {1, 2, 3, 4} and B = {x, y, z}, the Cartesian product A × B contains exactly ______ elements.

1. (A) 13
2. (B) 12 ✓
3. (C) 10
4. (D) 6

8. If f(x) = x² − 3x + 2, then the value of f(a + 1) is equal to:

1. (A) a + 1
2. (B) a² + 1
3. (C) a² + 2a + 1
4. (D) a² − a ✓

9. Given f(x) = 3x + 1, if f(x) = 28, then x is:

1. (A) 9 ✓
2. (B) 27
3. (C) 3
4. (D) 18

10. Let A = {1, 2, 3}, B = {a, b} and f : A → B be f = {(1, a), (2, b), (3, b)}. Which statement is true?

1. (A) f is injective
2. (B) f is surjective ✓
3. (C) f is bijective
4. (D) f is into only

11. A set with exactly one element is called:

1. (A) an empty set
2. (B) a universal set
3. (C) a power set
4. (D) a singleton set ✓

12. The set with no element is called:

1. (A) a singleton set
2. (B) a finite set
3. (C) the universal set
4. (D) the empty (null or void) set ✓

13. {0} is:

1. (A) an infinite set
2. (B) a disjoint set
3. (C) a singleton set ✓
4. (D) the empty set

14. The set of all vowels of the English alphabet in tabular form is:

1. (A) {a, e, i, o, u} ✓
2. (B) {a, b, c, d, e}
3. (C) {a, e, i, o}
4. (D) {b, c, d, f, g}

15. If a set S has m elements, the number of elements in its power set is:

1. (A) 2ᵐ ✓
2. (B) m²
3. (C) 2m
4. (D) m!

16. For A ⊆ B and A ≠ B the set A is called:

1. (A) an improper subset of B
2. (B) a superset of B
3. (C) equal to B
4. (D) a proper subset of B ✓

17. Two sets are equivalent if they have:

1. (A) no common element
2. (B) one common element
3. (C) the same number of elements ✓
4. (D) the same elements

18. A − B is the set of elements that:

1. (A) belong to A but not to B ✓
2. (B) belong to B but not to A
3. (C) belong to both A and B
4. (D) belong to neither A nor B

19. Two sets with no common element are called:

1. (A) disjoint sets ✓
2. (B) overlapping sets
3. (C) equal sets
4. (D) equivalent sets

20. The complement A' of a set A relative to U is equal to:

1. (A) U − A ✓
2. (B) A − U
3. (C) A ∩ U
4. (D) A ∪ U