a$)$ At $50C$ the vapour pressure of pure water and ethyl alcohol are $92\mathrm{.}5$ and $219\mathrm{.}9mm$ of $Hg$ respectively. If $6g$ of non$-$volatile solute with the molecular weight of $120$ is dissolved in $150g$ of each of these solvents, what will be the ratio of relative vapour pressure lowering in two solvents?