Half Adder_Digital Logic MCQ
1. A Half Adder is used to add:
A. Two decimal numbers
B. Two binary digits
C. Three binary digits
D. Two hexadecimal digits
Answer: B
Explanation: A Half Adder adds two 1-bit binary inputs.
2. Half Adder has:
A. Two inputs and one output
B. Two inputs and two outputs
C. Three inputs and one output
D. Three inputs and two outputs
Answer: B
Explanation:
Inputs: A, B
Outputs: Sum (S) and Carry (C)
3. Half Adder is a:
A. Sequential circuit
B. Memory device
C. Combinational circuit
D. Clocked circuit
Answer: C
4. Outputs of a Half Adder are:
A. Sum and Borrow
B. Difference and Carry
C. Sum and Carry
D. Carry and Overflow
Answer: C
5. Carry output of a Half Adder is generated when:
A. Any one input is 1
B. Both inputs are 0
C. Both inputs are 1
D. Inputs are different
Answer: C
Explanation: Carry = 1 only for A = 1 and B = 1.
6. Sum output of Half Adder is 1 when:
A. Both inputs are same
B. Both inputs are 1
C. Inputs are different
D. Both inputs are 0
Answer: C
7. For inputs A = 0, B = 1, the output of Half Adder is:
A. S = 0, C = 0
B. S = 1, C = 0
C. S = 0, C = 1
D. S = 1, C = 1
Answer: B
8. For inputs A = 1, B = 1, the output is:
A. S = 0, C = 0
B. S = 1, C = 0
C. S = 0, C = 1
D. S = 1, C = 1
Answer: C
9. Boolean expression for SUM in Half Adder is:
A. A + B
B. AB
C. A ⊕ B
D. (A + B)’
Answer: C
10. Boolean expression for CARRY in Half Adder is:
A. A + B
B. A ⊕ B
C. A’B + AB’
D. AB
Answer: D
11. Which logic gate is used to generate SUM?
A. AND
B. OR
C. XOR
D. NOR
Answer: C
12. Which logic gate is used to generate CARRY?
A. XOR
B. AND
C. OR
D. NAND
Answer: B
13. Half Adder can be implemented using:
A. AND and OR gates
B. XOR and AND gates
C. NAND gates only
D. NOR gates only
Answer: B
Explanation:
- SUM = XOR
- CARRY = AND
14. Half Adder cannot add:
A. Two bits
B. Binary numbers
C. Numbers with carry input
D. Single-bit numbers
Answer: C
Explanation: Half Adder has no carry input.
15. Half Adder differs from Full Adder because Half Adder:
A. Has carry input
B. Has three inputs
C. Has no carry input
D. Is a memory device
Answer: C
16. Half Adder is mainly used in:
A. Memory design
B. ALU design
C. CPU control unit
D. Sequential circuits
Answer: B
17. Which statement is TRUE?
A. Half Adder has carry input
B. Half Adder has two outputs
C. Half Adder is sequential
D. Half Adder uses clock
Answer: B
18. Half Adder can add multi-bit numbers directly.
A. True
B. False
Answer: B
19. Half Adder produces overflow.
A. True
B. False
Answer: B
Explanation: Overflow is related to signed multi-bit addition, not Half Adder.
20. Half Adder is a basic building block of:
A. Decoder
B. Encoder
C. Full Adder
D. Multiplexer
Answer: C
