The solution which have lowest freezing point is

Step-by-step solution

The freezing point depression is given by the formula T_f = i K_f m , where i is the van't Hoff factor, K_f is the cryoscopic constant, and m is the molality. Since K_f is constant for a given solvent and the molarity M is given as 0.2 M for all solutions, the freezing point depression is directly proportional to the van't Hoff factor i . The solution with the highest i will have the lowest freezing point. For 0.2 M K ₂ SO ₄ : K ₂ SO ₄ 2 K ⁺ + SO ₄²⁻ , so i = 3 . For 0.2 M KCl : KCl K ⁺ + Cl ⁻ , so i = 2 . For 0.2