Two moles of an ideal gas is expanded isothermally and reversibly from 1 litre to 10 litre at $300\mathrm{ }\mathrm{K}$. The internal energy change (in $\mathrm{KJ})$ for the process $(\mathrm{R}=8.3\mathrm{ }\mathrm{J})$

Given data: To find the change in internal energy of an isothermally and reversibly expansion of gas form 1 litre to 10 litre

Formula / Concept used: Thermodynamic processes - First law Detailed solution:

The work done formula for isothermally and reversible expansion is

$\mathrm{W}=-\mathrm{nRT}\log {\mathrm{V}}_2{/\mathrm{V}}_1$

Given, $n=2;R=8.3;T=300;V_2=10;V_1=1$

By substituting all the values we get $-11.4\mathrm{KJ}$ which is the change in enthalpy of the system

In an isothermal process, temperature remains constant. Internal energy is an function of temperature only

As there is no change in temperature there is no change in internal energy

Hence the correct option is (C).