Entropy in an irreversible cyclic process: behavior over one complete cycle Evaluate how the entropy of the system changes over a full irreversible cycle. Choose the correct statement.
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ARemains constant over the cycle
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BAlways increases over the cycle
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CAlways decreases over the cycle
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DUnpredictable change
Answer
Correct Answer: Remains constant over the cycle
Explanation
ConceptEntropy (S) is a state function. For any complete cycle (start and end at the same state), the change in entropy of the system is zero: ΔSsystem = 0, even if the processes are irreversible.
Important nuanceClausius inequality gives ∮ δQ/T < 0 for an irreversible cycle, but this integral is not equal to ΔSsystem over the cycle (which is zero by definition of a state function). The inequality reflects entropy generation in surroundings/universe, not a net change of the system after completing the loop.
Common pitfallsMixing up entropy of the system with entropy of the universe. The latter increases for overall spontaneous irreversible processes.
Final AnswerRemains constant over the cycle