where $W _{1}=$ Weight of the solute
$W _{2}= W$ eight of solvent
$M _{1}=$ Molar mass of solute
$K _{ f }= Freezing$ point depression constant
Now, $\quad \Delta T _{ f }=5.12 \times \frac{1 \times 1000}{51.2 \times 250}$
$\Delta T _{ f }=0.4 K$