Question

Freezing point of solution is marked as :-

$H_2O$

NaCl solution

Answer 1

A

Answer 2

The freezing point of a solution is lower than that of the pure solvent (freezing point depression). In the given vapor pressure-temperature graph, the upper curve represents pure $H_2O$ and the lower curve represents the NaCl solution. Point B is the freezing point of pure $H_2O$. Due to freezing point depression, the freezing point of the NaCl solution must be at a lower temperature than B. Point A is on the NaCl solution curve and is at a lower temperature than B. Thus, A represents the freezing point of the NaCl solution.