Q14 / 90 · JEE Main 2017 (09 Apr Online) · Chemistry

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

Correct answer
A
Enthalpy remains constant but entropy increases
B
Enthalpy decreases but entropy increases
C
Enthalpy increases but entropy decreases
D
Both enthalpy and entropy remain constant

Solution

ΔH = {nC}_{p} ΔT = 0, ∴ ΔT = 0

∴

P_ext = defined
so process is irreversible.

ΔS = nRln (V_{f} {/V}_{i}) \geq 0

Hence, the correct answer is option: 'A'.

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