PYQ NEET- Chemical Thermodynamics L-8

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

A) $\Delta U=0, \Delta S_{\text {total }}=0$

B) $\Delta U \neq 0, \Delta S_{\text {total }} \neq 0$

C) $\Delta U=0, \Delta S_{\text {total }} \neq 0$

D) $\Delta U \neq 0, \Delta S_{\text {total }}=0$

Answer: $\Delta U=0, \Delta S_{\text {total }} \neq 0$#

Solution:#

The change in internal energy depends on the temperature. For isothermal process, $\Delta T=0$.

So, $\quad \Delta U=0$.

With an expansion of an ideal gas, more space is available for the gaseous particles.

$\therefore$ Entropy of gas increases so, entropy of system is not zero.

i.e. $\quad \Delta S \neq 0$