Question

Which of the following is a colligative property?

(a) Relative lowering of fluid pressure

(b) Decrease in boiling point

(c) Decrease in freezing point

(d) Change in volume after mixing

I got this question in an internship interview.

Question is from Colligative Properties and Determination of Molar Mass topic in chapter Solutions of Chemistry – Class 12

Answer 1

Right option is (c) Decrease in freezing point

To explain I would say: Decrease in freezing point is the correct colligative property, known as ‘Depression in freezing point’. This is caused by solute particles present on the surface which lowers the equilibrium solid-vapor pressure. Therefore, a lower freezing temperature is required to match the pressure outside. The other correct colligative properties are 1.) Relative lowering of vapor pressure, 2.) Elevation in boiling point, 3.) Depression in freezing point and 4.) Osmotic pressure.