A substance ' X ' (1.5 g) dissolved in 150 g of a solvent 'Y' (molar mass =300 g mol^-1 ) led to an elevation of the boiling point by 0.5 K. The…

A substance ' $\displaystyle X$ ' ($\displaystyle 1.5$ g) dissolved in $\displaystyle 150$ g of a solvent 'Y' (molar mass $\displaystyle =300 \mathrm{~g} \mathrm{~mol}^{-1}$ ) led to an elevation of the boiling point by $\displaystyle 0.5$ K. The relative lowering in the vapour pressure of the solvent 'Y' is $\displaystyle \_\_\_\_$ $\displaystyle \times 10^{-2}$. (nearest integer) [Given : $\displaystyle \mathrm{K}_{\mathrm{b}}$ of the solvent $\displaystyle =5.0 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$ ] Assume the solution to be dilute and no association or dissociation of $\displaystyle X$ takes place in solution.