Question

For irreversible expansion of an ideal gas under isothermal condition, the correct option is :

• A. $\Delta U\ne 0,\Delta S_{total}\ne 0$
• B. $\Delta U=0,\Delta S_{total}\ne 0$
• C. $\Delta U\ne 0,\Delta S_{total}=0$
• D. $\Delta U=0,\Delta S_{total}=0$

Answer 1

The correct option is B

$\Delta U=0,\Delta S_{total}\ne 0$

For ideal gases, the change in internal energy is zero for an isothermal process since an ideal gas has no interactions between particles, no intermolecular forces, so pressure change at constant temperature does not change internal energy.
Hence, $\Delta U=0$

$\Delta S_{total}>0$

$\Delta U=0,\Delta S_{total}\ne 0$

Hence, option (b) is correct.