Question

\(\mathrm{K}_{\mathrm{t}}\) (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) \(-3.72^{\circ} \mathrm{C}\)
(C) \(-3.3^{\circ} \mathrm{C}\)
(D) \(-3^{\circ} \mathrm{C}\)

Answer 1

Ans: (C)
 \(\Delta \mathrm{T}_{\mathrm{f}}=\mathrm{K}_{\mathrm{f}} \times \mathrm{m}\)
$$
\begin{aligned}
&=1.86\left(\frac{10}{62} \times \frac{1000}{90}\right) \\
&=3.3^{\circ} \mathrm{C}
\end{aligned}
$$
\(\therefore\) Temparature at which ice begins to separate \(=3.3^{\circ} \mathrm{C}\)