The given degrees freedom for a gas= $n$

The total energy of the system, $U=\frac{n}{2}RT$ 

The molar specific heat at constant volume for given gas, $C_V=\frac{n}{2}R$ 

The molar specific heat at constant pressure for given gas, $C_P=C_V+R$ 

$C_P=\frac{n}{2}R+R$ 

$C_P=\left(\frac{n}{2}+1\right)R$ 

The ratio of specific heats of gas, $\frac{C_P}{C_V}=\frac{\left({\displaystyle \frac{n}{2}+1}\right){\displaystyle R}}{\left({\displaystyle \frac{n}{2}}\right){\displaystyle R}}$ 

$\frac{C_P}{C_V}=1+\frac{2}{n}$