Consider the following statements regarding Combinational Logic:1.Combinational circuits produce outputs based only on present input conditions without memory effect.2.These circuits do not include feedback paths or storage elements like flip-flops.3.Sequential logic is a subset of combinational circuits used for timing operations.Which of the above statements is/are correct?

Correct Answer: A - 1 and 2 only

Quick Concept Explanation

A useful classification test is whether the same present input can produce different outputs because of history. Adders, multiplexers, decoders and encoders are combinational; counters, registers and finite-state machines are sequential. Key relation: Combinational: y(t)=f[x(t)]. Sequential: y(t)=f[x(t), state(t)], with state(t+1)=g[x(t),state(t)].

Exam focus: Ask one question: “Does previous state matter?” If no → combinational. Common trap: Treating “timing operation” as proof that a circuit is combinational.

Statement-wise Verification

• Statement 1 - Correct.
  Combinational circuits produce outputs based only on present input conditions without memory effect.
  Combinational output is a function only of present inputs.
• Statement 2 - Correct.
  These circuits do not include feedback paths or storage elements like flip-flops.
  In the standard definition: combinational circuits contain logic gates without memory elements such as latches/flip-flops; intentional feedback that stores state belongs to sequential behavior.
• Statement 3 - Incorrect.
  Sequential logic is a subset of combinational circuits used for timing operations.
  Sequential logic is not a subset of combinational logic; it adds state/memory and often clocking.

Core Concept

A useful classification test is whether the same present input can produce different outputs because of history. If yes, the circuit is sequential. Adders, multiplexers, decoders and encoders are combinational; counters, registers and finite-state machines are sequential.

Formula / Key Relationship

Combinational: y(t)=f[x(t)]. Sequential: y(t)=f[x(t), state(t)], with state(t+1)=g[x(t),state(t)].

Step-by-Step Check

The definition validates 1 and 2 and directly rejects 3. Option A.

Why the Other Options Are Wrong

Option B is incorrect because it includes incorrect statement(s) 3 and omits correct statement(s) 1. Option C is incorrect because it includes incorrect statement(s) 3 and omits correct statement(s) 2. Option D is incorrect because it includes incorrect statement(s) 3.

Answer-Key Verification Note

The uploaded provisional key marks C . After independent technical verification, the defensible answer is A . This discrepancy is stated explicitly rather than silently copying the provisional key.

Exam Shortcut / Approach

Ask one question: “Does previous state matter?” If no → combinational.

Common Mistake

Treating “timing operation” as proof that a circuit is combinational.

Quick Revision

Memoryless Logic Circuits is linked with Combinational versus Sequential, Combinational Logic and Digital Electronics. Ask one question: “Does previous state matter?” If no → combinational.