Prove that the depression in freezing point is a colligative property.

Explanation

(i) The electrolyte NaCl dissociates completely into its constituent ions in their aqueous solution. This causes an increase in the total number of particles present in the solution.
(ii) When we dissolve 1 mole of NaCl in water. It, dissociates and gives 1 mole of `Na^(+)` and 1 mole of `Cl ^(-).` Hence the solution will have 2 moles of particles. But when we dissolve 1 mole of urea (non electrolyte) in water it appears as 1 mole only. So the colligative property value would be double in NaCl than in urea.