Question

The incorrect option for free expansion of ideal gas under isothermal condition is

• A. $\Delta H=0$
• B. $\Delta S=0$
• C. $\Delta T=0$
• D. $w=0$

Answer 1

The correct option is B $\Delta S=0$

(i) In free expansion $P_{\text{ext}}=0$ therefore $w=0$
(ii) For isothermal process
$\Delta H=n{C}_P\Delta T=0$
$\Delta U=n{C}_V\Delta T=0$
(iii) Entropy increases during the expansion