' W ' g of a non-volatile electrolyte solid solute of molar mass ' M ' g mol^-1 when dissolved in 100 mL water, decreases vapour pressure of water…

' W ' g of a non-volatile electrolyte solid solute of molar mass ' M ' $\displaystyle \mathrm{g} \mathrm{mol}^{-1}$ when dissolved in $\displaystyle 100$ mL water, decreases vapour pressure of water from $\displaystyle 640$ mm Hg to $\displaystyle 600$ mm Hg . If aqueous solution of the electrolyte boils at $\displaystyle 375$ K and $\displaystyle \mathrm{K}_{\mathrm{b}}$ for water is $\displaystyle 0.52 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$, then the mole fraction of the electrolyte solute $\displaystyle \left(\mathrm{x}_2\right)$ in the solution can be expressed as (Given : density of water $\displaystyle =1 \mathrm{~g} / \mathrm{mL}$ and boiling point of water $\displaystyle =373 \mathrm{~K}$ )