A: Paramagnetic sample displays greater magnetisation (for the magnetizing field) when cooled.
R: The tendency to disrupt the alignment of dipoles (with the magnetising field) arising from random thermal motion is reduced at lower temperatures.

Options

A. If both Assertion & Reason are the true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reson is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements, then mark (4)

Answer

To analyze the assertion and reason provided in the question, we can break down the explanation into clear steps:

### Step-by-Step Solution:

1. **Understanding Paramagnetism**:
- Paramagnetic materials have unpaired electrons that create magnetic dipoles. In the absence of an external magnetic field, these dipoles are randomly oriented, resulting in no net magnetization.

2. **Effect of Temperature on Paramagnetic Materials**:
- At higher temperatures, thermal energy causes increased random motion of the dipoles. This random thermal motion disrupts the alignment of the dipoles with an external magnetic field, leading to lower magnetization.

3. **Cooling the Paramagnetic Sample**:
- When the temperature of a paramagnetic sample is lowered, the thermal energy decreases. This reduction in thermal energy diminishes the random motion of the dipoles.

4. **Alignment of Dipoles**:
- With reduced random thermal motion, the dipoles are less likely to be disrupted and can align more effectively with the external magnetizing field. This results in an increase in magnetization.

5. **Conclusion**:
- Therefore, the assertion that a paramagnetic sample displays greater magnetization when cooled is correct. The reason provided is also valid, as it explains that the reduction in random thermal motion at lower temperatures leads to better alignment of the dipoles with the magnetizing field.

### Final Statement:
Both the assertion and the reason are correct. Thus, the conclusion is that the assertion is true and the reason correctly explains the assertion.

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