Equal moles of hydrogen and oxygen gases are placed in a container with a pin- hole through which both can escape. what fraction of the oxygen escapes in the time required for one half of the hydrogen to escape ?

Question

$\begin{array}{1 1} (a)\;\frac{1}{4} \\(b)\;\frac{3}{8} \\ (c)\;\frac{1}{2} \\ (d)\;\frac{1}{8} \end{array} $