An ideal gas undergoes a quasi static, reversible process in which its molar heat capacity Cremains constant. If during this process the relation of pressure P and volume V is given by $PV^n= constant$, then n is given by (Here $C_P$ and $C_V$ are molar specific heat at constant pressure and constant volume, respectively) :

Question

$\begin{array}{1 1} (1)n= \large\frac{C_p}{C_v} \\ (2)n= \large\frac{C-C_p}{C-C_v} \\ (3)n= \large\frac{C_p - C}{C-C_v} \\ (4)n= \large\frac{C-C_p}{C-C_p} \end{array}$