Question

Which of the following is not a colligative property?

• A. Vapour pressure
• B. Depression of freezing point
• C. Osmotic pressure
• D. Elevation of boiling point

Hint:

Colligative properties depend only on the number of solute particles and not on their nature or identity.

Answer 1

The Correct Option is A

Step 1: Understand colligative properties.
Colligative properties are properties that depend on the number of solute particles in a solution, not the identity of the solute particles. The common colligative properties include the depression of freezing point, elevation of boiling point, osmotic pressure, and vapour pressure lowering.
Step 2: Analyze each option.
- Vapour pressure is not a colligative property, as it depends on the nature of the solvent and solute. It is affected by the volatility of the solvent and solute, not just the number of particles. - The other properties listed (depression of freezing point, osmotic pressure, and elevation of boiling point) are all colligative properties.
Step 3: Apply to the options.
Since vapour pressure is not a colligative property, the correct answer is (A).
Final Answer: \[ \boxed{\text{Vapour pressure}} \]