Use the formula for depression in freezing point

$\Delta T_f = i K_f m$

where:

• $i$ = van’t Hoff factor
• $K_f = 4.0\ \text{kg mol}^{-1}$
• $m = 0.03\ \text{mol kg}^{-1}$

Find the van’t Hoff factor for $K_2SO_4$

Assuming complete dissociation:

$K_2SO_4 \rightarrow 2K^+ + SO_4^{2-}$

Total number of ions produced = $3$

Hence,

$i = 3$

Substitute into the formula

$\Delta T_f = 3 \times 4.0 \times 0.03$

$\Delta T_f = 0.36\ \text{K}$

Match with the options

$0.36\ \text{K}$ corresponds to Option C.

Comparison with stored correct answer

Stored correct answer = C

Derived answer = C

So they agree.