Multiple Choice Questions of Boolean Algebra & Logic gates

 

1. In Boolean algebra, the OR operation is performed by which properties?

A) Associative properties
B) Commutative properties
C) Distributive properties
D) All of the Mentioned

ANSWER= (D) All of the Mentioned
Explain:- The expression for Associative property is given by A+(B+C) = (A+B)+C & A*(B*C) = (A*B)*C. The expression for Commutative property is given by A+B = B+A & A*B = B*A. The expression for Distributive property is given by A+BC=(A+B)(A+C) & A(B+C) = AB+AC.

 

2. The expression for Absorption law is given by _________

A) A+AB=A
B) A+AB=B
C) AB+AĀ
D) A+B=B+A

ANSWER= (A) A+AB=A
Explain:- A + AB = A(1+B) = A (Since 1 + B = 1 as per 1’s Property).

 

 3. According to boolean law: A + 1 = ?

A) A
B) Ā
C) 1
D) 0

ANSWER= (C) 1

 

4. The involution of A is equal to _________

A) A
B) Ā
C) 0
D) 1

ANSWER= (A) A
Explain:- (Ā)'=A

 

5. A(A + B) = ?

A) AB
B) 1
C) 1+AB
D) A

ANSWER= (D) A
Explain:- A(A + B) = AA + AB (By Distributive Property) = A + AB (A.A = A By Commutative Property) = A(1 + B) = A*1 (1 + B = 1 by 1’s Property) = A

 

6. Which logic gate is represented by the following combination of logic gates?

A) OR
B) NAND
C) AND
D) NOR

ANSWER= (B) NAND

 

7. The output of OR gate is 1

A) If both inputs are zero
B) If either or both inputs are 1
C) Only if both inputs are 1
D) If either input is zero

ANSWER= (B) If either or both inputs are 1

 

8. Which of the following logic gate is a universal gate?

A) OR
B) AND
C) NOT
D) NOR

ANSWER= (D) NOR

 

9. A gate in which all the inputs must be low to get a high output is

A) NAND gate
B) Inverter
C) NOR gate
D) AND gate

ANSWER= (B) Inverter and (C) NOR gate,   both  

 

10. The outputs of a NAND gate is 0

A) If both inputs are 0
B) If one input is 0 and the other input is 1
C) If both inputs are 1
D) If both inputs are 1 or one of the inputs is 1 and the other one is 0

ANSWER= (C) If both inputs are 1

 

11. The following truth table corresponds to the logic gate

Input		Output
A	B	X
0	0	0
0	1	1
1	1	1
1	0	1

A) NAND
B) OR
C) AND
D) XOR

ANSWER= (B) OR

 

12. Boolean Algebra is essentially based on

A) Truth
B) Logic
C) Symbol
D) Numbers

ANSWER= (B) Logic

 

13. A logic gate is an electronic circuit which

A) Makes logic decisions.
B) Allows electrons flow only in one direction.   
C) Woks binary algebra.  
D) Alternates between 0 and 1 values. 

ANSWER= (A) Makes logic decisions.  

 

14. How many NAND gates are used to form an AND gate?

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

ANSWER= (B) 2

 

15. The boolean function A + BC is a reduced form of ____________

A) AB+BC
B) (A+B)(A+C)
C) ĀB+ABC
D) (A+C)B

ANSWER= (B)  (A+B)(A+C)
Explain:- (A + B)(A + C) = AA + AC + AB + BC = A + AC + AB + BC (By Commutative Property) = A(1 + C + B) + BC = A + BC (1 + B + C =1 By 1’s Property).

 

16. The inverter is __________

A) NOT gate
B) OR gate
C) AND gate
D) None of the above

ANSWER= (A) NOT gate

 

17. The inputs of a NAND gate are connected together. The resulting circuit is __________

A) NOT gate
B) OR gate
C) AND gate
D) None of the above

ANSWER= (A) NOT gate

 

18. The NOR gate is OR gate followed by __________

A) NOT gate
B) OR gate
C) AND gate
D) None of the above

ANSWER= (A) NOT gate

 

19. The NAND gate is AND gate followed by __________

A) NOT gate
B) OR gate
C) AND gate
D) None of the above

ANSWER= (A) NOT gate

 

20. Digital circuit can be made by the repeated use of __________

A) NOT gate
B) OR gate
C) NAND gate
D) None of the above

ANSWER= (C) NAND gate