Which of the following 0.1 M aqueous solutions will have the lowest freezing point?

K₂SO₄

The correct answer is option 1. \(K_2SO_4\)

To determine which of the following 0.1 M aqueous solutions will have the lowest freezing point, we need to consider the colligative property of freezing point depression. The freezing point of a solution is lowered compared to the pure solvent due to the presence of solute particles.

The degree of freezing point depression depends on the concentration of solute particles in the solution. Substances that dissociate or ionize into more particles will have a greater impact on lowering the freezing point.

(1) $\text{K}_2\text{SO}_4$: $\text{K}_2\text{SO}_4$ dissociates into three ions in water: $2\text{K}^+$ and $\text{SO}_4^{2-}$. It contributes three solute particles to the solution.

(2) $\text{NaCl}$: $\text{NaCl}$ dissociates into two ions in water: $\text{Na}^+$ and $\text{Cl}^-$. It contributes two solute particles to the solution.

(3) Urea: Urea does not dissociate or ionize in water. It remains as individual molecules in the solution, contributing only one solute particle

(4) Glucose: Glucose also does not dissociate or ionize in water. It remains as individual molecules in the solution, contributing only one solute particle.

Based on the number of solute particles, the solution of $\text{K}_2\text{SO}_4$ (1) will have the lowest freezing point because it provides the highest number of solute particles. The dissociation of $\text{K}_2\text{SO}_4$ into three ions leads to a greater degree of freezing point depression compared to the other options.