# Discrete Structure (DS) Solved MCQs

Chapters

Chapter: Unit 1
1.

A. 1
B. 2
C. 3
D. 4
2.

## Let A={2,{4,5},4} Which statement is correct?

A. 5 is an element of A.
B. {5} is an element of A.
C. {4, 5} is an element of A.
D. {5} is a subset of A.
Answer» C. {4, 5} is an element of A.
3.

## Which of these sets is finite?

A. {x | x is even}
B. ) {1, 2, 3,...}
C. {1, 2, 3,...,999,1000}
D. none
4.

## Which of these sets is not a null set?

A. A = {x | 6x = 24 and 3x = 1}
B. B = {x | x + 10 = 10}
C. C = {x | x is a man older than 200 years}
D. D = {x | x < x}
Answer» B. B = {x | x + 10 = 10}
5.

A. 3
B. 6
C. 8
D. 4
6.

## . Which set S does the power set 2S = {Ф,{1}, {2}, {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3}} come from?

A. {{1},{2},{3}}
B. {1, 2, 3}
C. {{1, 2}, {2, 3}, {1, 3}}
D. {{1, 2, 3}}
7.

## Let A = {x, y, z}, B = {v, w, x}. Which of the following statements is correct?

A. A U B ={v, w, x, y, z}
B. A U B = {v, w, y, z}
C. A U B = {v, w, x, y}
D. A U B ={x, w, x, y, z}
Answer» A. A U B ={v, w, x, y, z}
8.

A. 1 and 2
B. 2 and 3
C. 1 and 3
D. all are equal
9.

## A U A=A according to …….law

A. Associative law
B. commutative law
C. Indempotent law
D. distributive law
10.

A. union
B. intersection
C. universal
D. cardinal
11.

A. TRUE
B. FALSE
C. Both
D. None
12.

A. TRUE
B. FALSE
C. Both
D. None
13.

A. TRUE
B. FALSE
C. Both
D. None
14.

A. TRUE
B. FALSE
C. Both
D. None
15.

A. TRUE
B. FALSE
C. Both
D. None
16.

## one of the A or B is uncountably infinite and one is countably infinite then | AUB| will be

A. countably infinite
B. uncountably finite
C. countably finite
D. uncountably infinite
17.

A. n(n+1)
B. n
C. n(n+1)0.5
D. n(n+2)
18.

## Let P(S) denote the power set of set S. which of the is always true

A. P(P(s))=p(s)
B. P(S)∩ S= P(S)
C. P(S)∩P(P(S)) ={Ф}
D. None
19.

A. TRUE
B. FALSE
C. Both
D. None
20.

A. 100
B. 25
C. 56
D. 20
21.

A. Multiset
B. ordered set
C. set
D. None
22.

A. 9
B. 8
C. 7
D. 6
23.

## If U = {1, 2, 3, . . . 10 } and S = { 4, 5, 6, 7, 8 }, then S ' =

A. { 9, 10 }
B. {1, 2, 3 }
C. {1, 2, 3 9 }
D. {1, 2, 3 9 10 }
Answer» D. {1, 2, 3 9 10 }
24.

## If U = {1, 2, 3, . . . 20 } and S = set of prime numbers , then S =

A. { 3, 5, 7, 11, 13, 17 }
B. { 2, 3, 5, 7, 11, 13, 17, 19 }
C. {1, 3, 5, 7, 9, 11, 13, 15, 17, 19 }
D. {1, 2, 3, 5, 7, 11, 13, 17 }
Answer» B. { 2, 3, 5, 7, 11, 13, 17, 19 }
25.

## Consider the statement,“If n is divisible by 30 then n is divisible by 2 and by 3 and by 5.”Which of the following statements is equivalent to this statement?

A. If n is not divisible by 30 then n is divisible by 2 or divisible by 3 or divisible by 5
B. If n is not divisible by 30 then n is not divisible by 2 or not divisible by 3 or not divisible by 5
C. If n is divisible by 2 and divisible by 3 and divisible by 5 then n is divisible by 30.
D. If n is not divisible by 2 or not divisible by 3 or not divisible by 5 then n is not divisible by 30
Answer» D. If n is not divisible by 2 or not divisible by 3 or not divisible by 5 then n is not divisible by 30
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