Question

Which of the following properties is NOT a colligative property?

• A. elevation in boiling point
• B. osmotic pressure
• C. vapour pressure of solvent
• D. depression in freezing point

Hint:

Remember, colligative properties include the {change} in vapour pressure, not the vapour pressure itself.

Answer 1

The Correct Option is C

Step 1: Understanding colligative properties.
Colligative properties are those properties of solutions which depend only on the number of solute particles present in the solution and not on their nature. These properties arise due to the presence of solute particles.
Step 2: Listing the colligative properties.
The four main colligative properties are:
elevation in boiling point,
depression in freezing point,
lowering of vapour pressure,
and osmotic pressure.
Step 3: Analyzing the options.
(A) Elevation in boiling point: This is a colligative property because it depends on the number of solute particles.
(B) Osmotic pressure: This is also a colligative property and depends on solute concentration.
(C) Vapour pressure of solvent: Vapour pressure itself is not a colligative property. Only the lowering of vapour pressure is considered a colligative property.
(D) Depression in freezing point: This is a colligative property.
Step 4: Conclusion.
Since vapour pressure of solvent is not directly a colligative property, option (C) is correct.