'W' g of a non-volatile electrolyte... | Solutions

JEE MAIN 2026

24-01-26 S1

Question

'W' g of a non-volatile electrolyte solid solute of molar mass ${ }^{\prime} \mathrm{M}^{\prime} \mathrm{gmol}^{-1}$ when dissolved in 100 mL water, decreases vapour pressure of water from 640 mm Hg to 600 mm Hg . If aqueous solution of the electrolyte boils at $375 \mathrm{~K}^{\circ}$ and $\mathrm{K}_{\mathrm{b}}$ for water is $0.52 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$, then the mole fraction of the electrolyte solute ( $x_2$ ) in the solution can be expressed as (Given : density of water $=1 \mathrm{~g} / \mathrm{mL}$ and boiling point of water $=373 \mathrm{~K}$ )

Select the correct option:

$\frac{1.3}{8} \times \frac{W}{M}$

$\frac{16}{2 \cdot 6} \times \frac{W}{M}$

$\frac{2 \cdot 6}{16} \times \frac{\mathrm{M}}{\mathrm{W}}$

$\frac{1.3}{8} \times \frac{\mathrm{M}}{\mathrm{W}}$

✓ Correct! Well done.

✗ Incorrect. Try again or view the solution.

Solution