Previous Year NEET Question- Solution L-3

Question: The freezing point depression constant $\left(\mathrm{K}_{\mathrm{r}}\right)$ of benzene is $5.12 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$. The freezing point depression for the solution of molality $0.078 \mathrm{~m}$ containing a non-electrolyte solute in benzene is rounded off upto two decimal places :#

A) $0.80 \mathrm{~K}$

B) $0.40 \mathrm{~K}$

C) $0.60 \mathrm{~K}$

D) $0.20 \mathrm{~K}$

Answer: $0.40 \mathrm{~K}$#

Solution:#

$\begin{aligned} & \Delta T_f=k_f m \ & =5.12 \times 0.078 \ & =0.399 \mathrm{~K}=0.4 \mathrm{~K}\end{aligned}$