$\begin{aligned} & \mathrm{K}_2 \mathrm{SO}_4 \longrightarrow 2 \mathrm{~K}^{+}+\mathrm{SO}_4^{2-} \\ & \mathrm{i}(\text { Van't Hoff Factor })=3 \\ & \begin{aligned} \therefore \Delta \mathrm{Tf} & =\mathrm{i} \mathrm{K}_{\mathrm{f}} \mathrm{m} \\ & =3 \times 4 \times 0.03 \\ & =0.36 \mathrm{~K}\end{aligned}\end{aligned}$