At room temperature $25^{\large\circ}C$,the vapour pressure of pure methyl alcohol is 90 torr.Mol fraction of $CH_3OH$ in a solution in which vapour pressure of $CH_3OH$ is 20 torr at $25^{\large\circ}$ is ?

Question

$\begin{array}{1 1}(a)\;0.30\\(b)\;0.22\\(c)\;0.40\\(d)\;0.50\end{array}$