$C_p$ and $C_v$ are specific heats at constant pressure and constant volume respectively. It is observed that $C_p−C_v=a$ for hydrogen gas $Cp−Cv=b$ for nitrogen gas The correct relation between a and b is :

Question

$\begin{array}{1 1}(1) a= \large\frac{1}{14} b \\(2) a=b \\(3) a=14 b \\(4) a=28 b \end{array}$