Which flask has the solution with the lowest freezing point

Here's what I get  

Explanation:

Assume you have 0. 1 mol·kg⁻¹ solutions of A) KCl, B) CH₃OH, C) Ba(OH)₂, and D) CH₃COOH.

The formula for freezing point depression is

Where

  b = the molal concentration

K_f = the freezing point depression constant

    i = the van't Hoff i factor

The i-factor is the number of solute particles produced by one formula unit of the substance.

The only difference in the solutions is the i-factor of the solutes.

A) KCl

KCl(aq) ⟶ K⁺(aq) +Cl⁻(aq); i = 2

B) CH₃OH

Methanol is a nonelectrolyte.

CH₃OH(aq) ⟶ CH₃OH(aq); i = 1

C) Ba(OH)₂

Ba(OH)₂(aq) ⟶ Ba²⁺(aq) + 2OH⁻(aq); i = 3

D) CH₃COOH

CH₃COOH(aq) ⇌ CH₃COO⁻(aq)+ H⁺(aq); i ⪆ 1

The Ba(OH)₂ solution has the greatest i-value. It therefore has the greatest freezing point depression and the lowest freezing point.