Chemistry Question from JEE Main 2026 · 24 January, Shift 1

$W$ g of a non-volatile electrolyte solid solute of molar mass $M \, \text{g mol}^{-1}$ when dissolved in $100 \, \text{mL}$ water decreases vapour pressure of water from $640 \, \text{mm Hg}$ to $600 \, \text{mm Hg}$. If aqueous solution of the electrolyte boils at $375 \, \text{K}$ and $K_b$ for water is $0.52 \, \text{K kg mol}^{-1}$, then the mole fraction of the electrolyte $(x_2)$ in the solution can be expressed as

(Given: density of water $= 1 \, \text{g mL}^{-1}$, boiling point of water $= 373 \, \text{K}$)