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JEE Main2017ChemistryThermodynamics (C)Actual

An ideal gas undergoes isothermal expansion at constant pressure. During the process:

Options

  1. AEnthalpy remains constant but entropy increases
  2. BEnthalpy decreases but entropy increases
  3. CEnthalpy increases but entropy decreases
  4. DBoth enthalpy and entropy remain constant

Correct answer

A. Enthalpy remains constant but entropy increases

Step-by-step solution

ΔH   =   nC p   ΔT   =   0,         ∴   ΔT   =   0 ∴ P ext = defined so process is irreversible. ΔS   =   nRln  V f /V i ≥ 0

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