The depression in freezing point ($\Delta T_f$) is a colligative property calculated using the formula: $\Delta T_f = i \times K_f \times m$

Where: $K_f$ = Freezing point depression constant = $5.12 \text{ K kg mol}^{-1}$ $m$ = Molality of the solution = $0.078 \text{ mol kg}^{-1}$

• $i$ = Van't Hoff factor. Since the solute is a non-electrolyte, it does not dissociate or associate, so $i = 1$ .

Calculation: $\Delta T_f = 1 \times 5.12 \times 0.078$ $\Delta T_f \approx 0.39936 \text{ K}$

Rounding to two decimal places, $\Delta T_f = 0.40 \text{ K}$.