Arrange the following aqueous solutions in the increasing order of their freezing points: (I) 0.10 M Urea (II) 0.04 M K ₂ SO ₄ (III) 0.05 M BaCl ₂ (IV) 0.04 M Al ₂( SO ₄)₃ Assume complete dissociation for the electrolytes.

Step-by-step solution

The depression in freezing point is given by T_f = i K_f m i K_f C . The freezing point of the solution is T_f = T_f^ - T_f . Thus, a higher value of effective concentration ( i C ) results in a greater depression in freezing point, which means a lower freezing point. Let us calculate i C for each solution: (I) Urea: Non-electrolyte, i = 1 . i C = 1 0.10 = 0.10 (II) K ₂ SO ₄ : Dissociates into 2 K ^+ and SO ₄²⁻ , i = 3 . i C = 3 0.04 = 0.12 (III) BaCl ₂ : Dissociates into Ba ²⁺ and 2 Cl ^- , i = 3 . i C = 3 0.05 =