Question

Which of the following are Combinational Circuit?
• [A.] Half adder
• [B.] SR flip-flop
• [C.] Full adder
• [D.] D flip-flop
Choose the correct answer from the options given below:

• A. A and C only
• B. B and D only
• C. B, C, D only
• D. A, B, C, D

Hint:

Adders → combinational, Flip-flops → sequential.

Answer 1

The Correct Option is A

Concept: Digital circuits are classified into:
• Combinational circuits → output depends only on present input
• Sequential circuits → output depends on past and present inputs

Step 1: Analyze Half Adder (A).
• Performs addition using current inputs only
• No memory element ✔ Combinational

Step 2: Analyze SR Flip-Flop (B).
• Has memory
• Depends on previous state ✘ Sequential

Step 3: Analyze Full Adder (C).
• Uses present inputs only
• No storage element ✔ Combinational

Step 4: Analyze D Flip-Flop (D).
• Stores data
• Depends on clock and previous state ✘ Sequential

Step 5: Conclusion. \[ \boxed{(1)\ A \text{ and } C\ \text{only}} \]