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GATE 2023 CH – Question 19

Thermodynamics · Laws of thermodynamics, open and closed systems, entropy and chemical potential · 1 mark · Multiple choice

John and Jane independently performed a thermodynamic experiment, in which X and Y represent the initial and final thermodynamic states of the system, respectively. John performed the experiment under reversible conditions, for which the change in entropy of the system was $\Delta S_{rev}$. Jane performed the experiment under irreversible conditions, for which the change in entropy of the system was $\Delta S_{irr}$. Which one of the following relationships is CORRECT?

  1. $\Delta S_{rev} = \Delta S_{irr}$
  2. $\Delta S_{rev} > \Delta S_{irr}$
  3. $\Delta S_{rev} < \Delta S_{irr}$
  4. $\Delta S_{rev} = 2\Delta S_{irr}$

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Correct answer: (A) $\Delta S_{rev} = \Delta S_{irr}$

Explanation

Entropy is a state function, so its change depends only on the initial and the final states, X and Y, and not on the path. The entropy change of the system is the same in both experiments. (The entropy of the surroundings or the universe differs.)