Logic Gates & Switching Circuits MCQs

Digital Electronics MCQs

1. Which of the following logic gate follow both commutative and associative law?

a. AND gate

b. NAND gate

c. NOR gate

d. None of these

2. The minimum number of NOR gates requires to implement the expression f(A, B, C) = πM(0, 1, 2, 3, 4, 7) is______.

a. 6

b. 7

c. 4

d. 5

3. The number of two input NAND gate required to implement an OR gate and an EX-NOR gate are respectively______.

a. 2 and 4

b. 3 and 5

c. 3 and 4

d. 2 and 5

4. If one of the input to an EX-NOR gate is fixed to logic '1', then the output of this gate will be______.

a. Logic '1'

b. Same as input

c. Logic '0'

d. Complement of its input

5. An AND gate______.

a. Gives high output only when all inputs are low

b. Is equivalent to a series switching circuit

c. Implements logic addition

d. Is equivalent to a parallel switching circuit

6. An XOR gate produces output 1 only when two inputs are____.

a. Equal

b. Low

c. High

d. Different

7. A logic gate is an electronic circuit which______.

a. Performs arithmetic and logic functions

b. Operates on binary algebra

c. Alternates between 0 and 1 values

d. Allows flow of electrons only in one direction

8. The output of a logic gate is '0' when both its inputs are different. The gate is_____.

a. Either an EX-NOR or NOR gate

b. Either an EX-OR or NOR gate

c. Either an EX-NOR or NAND gate

d. Either an EX-OR or NAND gate

9. A circuit has three inputs and one output. The output is 1 if at least two of the three input variables are 1, otherwise it is zero. The minimum number of basic gates required to implement the output(Y) are_____.

a. 8

b. 7

c. 4

d. 3

10. In the truth table of an N-input OR gate, in the column for the output of the gate,______.

a. The number of times a zero occurs is a complex function of N

b. The output is zero if any one of the input is zero

c. The number of zeros is always 1

d. The number of zeros is equal to N

11. Assertion (A): When a number of variables are to be X-NORed, a number of two-input X-NOR

gates can be used.

Reason (R): Three or more variable X-NOR gates will make the circuit costly.

a. A is false but R is true

b. A is true but R is false

c. Both A and R true but R is not the correct explanation of A

d. Both A and R are true and R is the correct explanation of A