Which of the following is a colligative property ?

Options

A. Surface tension
B. Osmotic pressure
C. Optical rotation
D. Viscosity

Answer

To determine which of the following is a colligative property, we first need to understand what colligative properties are.

### Step-by-Step Solution:

1. **Definition of Colligative Properties**:
- Colligative properties are properties of solutions that depend on the number of solute particles in a given amount of solvent, rather than the identity of the solute itself.

2. **Types of Colligative Properties**:
- There are four main types of colligative properties:
- **Relative lowering of vapor pressure**
- **Elevation in boiling point**
- **Depression in freezing point**
- **Osmotic pressure**

3. **Identifying the Colligative Property**:
- From the options provided, we need to identify which one of them is a colligative property.
- For example, if the options include osmotic pressure, elevation in boiling point, depression in freezing point, and relative lowering of vapor pressure, all of these are colligative properties.

4. **Conclusion**:
- If the question specifically asks for one of the options, we can conclude that osmotic pressure is indeed a colligative property as it is directly related to the concentration of solute particles in a solution.

5. **Final Answer**:
- Therefore, the correct answer is **option B: Osmotic Pressure**.