Equal weights of Methane and Oxygen are mixed in an empty container at $25^{\circ}C$. The fraction of the total pressure exerted by Oxygen is :

Question

$\begin {array} {1 1} (1)\;\large\frac{1}{2} & \quad (2)\;\large\frac{2}{3} \\ (3)\;\large\frac{1}{4} & \quad (4)\;\large\frac{1}{3} \end {array}$