Four aqueous solutions each contain $5.0 mol$ of water: (X) $0.20 mol$ urea; (Y) $0.10 mol$ $K X_{2} SO X_{4}$ ; (Z) $0.15 mol$ $NaCl$ ; (W) $0.25 mol$ glucose. Assume complete dissociation of electrolytes and that every ion is an independent particle. Which statements are correct?

Answer: A, B, C

Particles: X

= 0.20

, Y

= 3 \times 0.10 = 0.30

, Z

= 2 \times 0.15 = 0.30

, W

= 0.25 mol

. Relative lowering

= n / (5.0 + n)

: X

= 0.0385

, Y

= Z = 0.0566

, W

= 0.0476

. Y and Z are equal (1 true, 4 false), X has the smallest lowering and so the highest vapour pressure (2 true), and W

\approx 0.0476

(3 true). Answer: 1, 2 and 3.