Question

Which one is a colligative property?

• A. Boiling point
• B. Vapour pressure
• C. Osmotic pressure
• D. Freezing point

Answer 1

The Correct Option is C

To determine which one is a colligative property, it is important to understand the concept of colligative properties. Colligative properties are properties of solutions that depend on the number of solute particles in a solvent, and not on the identity of the solute. There are four main colligative properties:

1. Vapor pressure lowering
2. Boiling point elevation
3. Freezing point depression
4. Osmotic pressure

Let's analyze each option one by one:

• Boiling point: Although boiling point is affected by the presence of solute, it is not a colligative property itself. Instead, the relevant colligative property is the boiling point elevation, which refers to the increase in boiling point due to solute.
• Vapour pressure: Like boiling point, vapour pressure itself is not a colligative property. The appropriate colligative property here is vapor pressure lowering, which is the decrease in vapour pressure as a result of adding a solute to the solvent.
• Osmotic pressure: Osmotic pressure is a colligative property. It is the pressure required to stop the process of osmosis, which occurs when a solvent flows through a semipermeable membrane from a dilute solution to a more concentrated one.
• Freezing point: While freezing point is affected by additions of solute, the relevant colligative property is the freezing point depression, which is the decrease in freezing point due to solute.

From the above analysis, it is clear that Osmotic pressure is the correct answer as it is one of the four recognized colligative properties.