One mole of an ideal gas is taken from state A to state B by three different processes (a) ACB, (b) ADB and (c) AEB as shown in the P-V diagram. The heat absorbed by the gas is

Heat absorbed by gas in three processes is given by

$\begin{array}{l}{\mathrm{Q}}_{\mathrm{ACB}}=\mathrm{\Delta U}+{\mathrm{W}}_{\mathrm{ACB}}\\ {\mathrm{Q}}_{\mathrm{ADB}}=\mathrm{\Delta U}\\ {\mathrm{Q}}_{\mathrm{AEB}}=\mathrm{\Delta U}+{\mathrm{W}}_{\mathrm{AEB}}\end{array}$

The change in internal energy in all the three cases is same and ${\mathrm{W}}_{\mathrm{ACB}}$ is positive, ${\mathrm{W}}_{\mathrm{AEB}}$, it negative.

$\text{ Hence }{\mathrm{Q}}_{\mathrm{ACB}}>{\mathrm{Q}}_{\mathrm{ADB}}>{\mathrm{Q}}_{\mathrm{AEB}}$