250+ TOP MCQs on Logic Gates and Answers

Computer Fundamentals Multiple Choice Questions on “Logic Gates”.

1. Electronic circuits that operate on one or more input signals to produce standard output _______
a) Series circuits
b) Parallel Circuits
c) Logic Signals
d) Logic Gates

Answer: d
Clarification: The logic gates operate on one or more input signals to produce a standard output.
Logic gates give the output in the form of 0 and 1.
The Boolean algebra can be applied to the logic gates.

2. Logic Gates are the building blocks of all circuits in a computer.
a) True
b) False

Answer: a
Clarification: The statement is true.
Logic gates are idealized to implement a boolean function in all circuits of a computer.
The signals are directed as per the outputs of the logic gates in the form of 0 and 1.

3. A __________ gate gives the output as 1 only if all the inputs signals are 1.
a) AND
b) OR
c) EXOR
d) NOR

Answer: a
Clarification: The AND gate gives a 1 only if all the input signals are 1.
The Boolean expression for evaluating an AND signal is: Y=A.B.

4. The boolean expression of an OR gate is _______
a) A.B
b) A’B+AB’
c) A+B
d) A’B’

Answer: c
Clarification: An OR gate gives the result as 1 if any one of the inputs is one.
Its expression is A+B.
An OR gate gives a 0 only if both the inputs are 0.

5. The gate which is used to reverse the output obtained is _____
a) NOR
b) NAND
c) EXOR
d) NOT

Answer: d
Clarification: NOT gate is used to reverse the output from 0 to 1 and vice-versa.
The Boolean expression for NOT gate is Y=A’.
Therefore, it gives the complement of the result obtained.

6. Which of the following gate will give a 0 when both of its inputs are 1?
a) AND
b) OR
c) NAND
d) EXOR

Answer: c
Clarification: The NAND gate gives 0 as the output when both of its inputs are 1 or any one of the input is 1.
It returns a 1 only if both the inputs are 0.

7. When logic gates are connected to form a gating/logic network it is called as a ______________ logic circuit.
a) combinational
b) sequential
c) systematic
d) hardwired

Answer: a
Clarification: It is referred to as a combinational circuit as it comprises a number of gates.
It is connected to evaluate a result of a Boolean expression.

8. The universal gate that can be used to implement any Boolean expression is __________
a) NAND
b) EXOR
c) OR
d) AND

Answer: a
Clarification: NAND gate can be used to implement any Boolean expression.
It is a universal gate. A universal gate can be used to implement any other Boolean function without using any other logic gate.

9. The gate which is called an inverter is called _________
a) NOR
b) NAND
c) EXOR
d) NOT

Answer: d
Clarification: Inverter is used to reverse the output. A NOT gate is used to invert or change the output from 0 to 1 and vice-versa.

10. The expression of an EXOR gate is ____________
a) A’B+AB’
b) AB+A’B’
c) A+A.B
d) A’+B’

Answer: a
Clarification: The expression for an EXOR gate is A’B+AB’.
An EXOR gate is nothing but an exclusive OR gate.