Four aqueous solutions of non-electrolytes are prepared: (i) $4.5 g$ urea (M $= 60$ ) in $150 g$ water, (ii) $9.0 g$ glucose (M $= 180$ ) in $90 g$ water, (iii) $17.1 g$ sucrose (M $= 342$ ) in $100 g$ water, (iv) $4.6 g$ glycerol (M $= 92$ ) in $100 g$ water. Which solution has the lowest freezing point?

Answer: B

All solvents are water, so the solution with the highest molality has the largest

Δ T_{f}

. Molalities: (i) 0.500, (ii) 0.556, (iii) 0.500, (iv) 0.500

mol k g^{- 1}

. The glucose solution is the most concentrated, so it freezes at the lowest temperature.