a
${\mathrm{VT}=\mathrm{K}} $
${\Rightarrow \quad \mathrm{V}\left(\frac{\mathrm{PV}}{\mathrm{nR}}\right)=\mathrm{k}} $
${\Rightarrow \quad \mathrm{PV}^{2}=\mathrm{K}} $
${\because \quad \mathrm{C}=\frac{\mathrm{R}}{1-\mathrm{x}}+\mathrm{C}_{\mathrm{v}} \text { (For polytropic process) }} $
${\mathrm{C}=\frac{\mathrm{R}}{1-2}+\frac{3 \mathrm{R}}{2}=\frac{\mathrm{R}}{2}} $
${\therefore \quad \Delta \mathrm{Q}=\mathrm{nC} \Delta \mathrm{T}}$