Which of the following aqueous solutions will have the highest freezing point? (Assume complete dissociation for strong electrolytes)

Step-by-step solution

Depression in freezing point is given by T_f = i K_f m . Assuming molality is approximately equal to molarity for dilute solutions, T_f i M . The freezing point of the solution is T_f = T_f^ - T_f . To have the highest freezing point, the solution must exhibit the minimum depression in freezing point ( T_f ), which corresponds to the lowest effective concentration ( i M ). Calculating i M for each given solution: 1. 0.15 M NaCl : i = 2 ( Na ^+, Cl ^- ), so i M = 2 0.15 = 0.30 2. 0.2 M Urea: i = 1 (non-electrolyte),