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NEETChemistryThermodynamics (C)

Consider an ideal gas undergoing a reversible Carnot cycle. Read the following statements regarding the entropy changes during the processes: Statement I: The total entropy change of the universe for the complete reversible cycle is zero. Statement II: The entropy change of the system during the isothermal expansion step is positive. Statement III: The entropy change of the system during the adiabatic compression ste

Options

  1. A4
  2. B3
  3. C2
  4. D1

Correct answer

B. 3

Step-by-step solution

Statement I is correct: For any reversible process, the total entropy change of the universe (system + surroundings) is always zero. Statement II is correct: During isothermal expansion, the gas absorbs heat reversibly ( q_ rev > 0 ). Since S = q_ rev T , the entropy change of the system is positive. Statement III is incorrect: A reversible adiabatic process involves no heat exchange ( q_ rev = 0 ). Therefore, the entropy change of the system is zero ( S = 0 ), not negative. It is an isentropic process. Statement I

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