Assertion (A) Colloidal solution show colligative properties.
Reason (R) Colloidal particles are large in size.

Options

A. Assertion and reason both are correct and the reason is correct explanation of assertion.
B. Assertion and reason both are correct but reason does not explain assertion.
C. Assertion is correct, but reason is incorrect.
D. Both assertion and reason are incorrect.

Explanation

To analyze the assertion and reason given in the question, we will break down the concepts step by step.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Colloidal solutions show colligative properties."
- **Colligative properties** are properties that depend on the number of solute particles in a solution, not their identity. Examples include boiling point elevation, freezing point depression, and osmotic pressure.

2. **Evaluating the Assertion**:
- Colloidal solutions do exhibit colligative properties, but the extent of these properties is generally much smaller compared to true solutions (like salt or sugar dissolved in water).
- Therefore, the assertion is **correct**.

3. **Understanding the Reason**:
- The reason states that "Colloidal particles are large in size."
- Colloidal particles are indeed larger than those in true solutions, typically ranging from 1 nm to 1000 nm in diameter.

4. **Evaluating the Reason**:
- While it is true that colloidal particles are large, this fact does not explain why colloidal solutions exhibit colligative properties. The presence of fewer, larger particles in a colloidal solution means that the colligative properties are less pronounced compared to true solutions, where there are more solute particles.
- Thus, while the reason is **true**, it does not adequately explain the assertion.

5. **Conclusion**:
- Since the assertion is correct and the reason is also correct but does not explain the assertion, the correct option is that both assertion and reason are correct, but the reason does not explain the assertion.

### Final Answer:
The correct option is **B**: Assertion and reason are both correct, but the reason does not explain the assertion.

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