Solutions · Relative lowering of vapour pressure

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 relative lowering in the vapour pressure of the solvent ‘Y' is $\times10^{-2}$. (Nearest integer)

[Given : $K_\mathrm{b}$ of the solvent $= 5.0$ K kg mol$^{-1}$]

Assume the solution to be dilute and no association or dissociation of X takes place in solution.