Q16 / 155 · WBJEE 2020 · Chemistry
$\mathrm{K}_{f}$ (water) $=1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$. The temperature at which ice begins to separate from a mixture of 10 mass $\%$ ethylene glycol is
- A$-1.86^{\circ} \mathrm{C}$
- B$-3.72^{\circ} \mathrm{C}$
- Correct answerC$-3.3^{\circ} \mathrm{C}$
- D$-3^{\circ} \mathrm{C}$
Solution
Hint:
$\Delta \mathrm{T}_{\mathrm{f}}=\mathrm{K}_{\mathrm{f}} \times \mathrm{m}$
$=1.86\left(\frac{10}{62} \times \frac{1000}{90}\right)$
$=3.3^{\circ} \mathrm{C}$
$\therefore$ Temparature at which ice begins to separate $=3.3^{\circ} \mathrm{C}$
Hence, the correct answer is option: 'C'.