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 solve the question, we need to analyze both the assertion (A) and the reason (R) provided.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that a paramagnetic sample displays greater magnetization when cooled.
- In paramagnetic materials, the magnetic dipoles tend to align with an external magnetic field. The strength of this alignment, and thus the magnetization, increases as the temperature decreases.

2. **Understanding the Reason (R)**:
- The reason provided explains that the tendency to disrupt the alignment of dipoles (with the magnetizing field) due to random thermal motion is reduced at lower temperatures.
- At higher temperatures, thermal energy causes more random motion of the atoms and dipoles, leading to a greater tendency for misalignment. Cooling the sample reduces this thermal motion, allowing for better alignment of the dipoles.

3. **Connecting Assertion and Reason**:
- The assertion is correct because cooling a paramagnetic sample indeed leads to greater magnetization.
- The reason is also correct as it accurately describes why cooling reduces the disruption of dipole alignment due to decreased thermal motion.

4. **Conclusion**:
- Both the assertion (A) and the reason (R) are correct, and the reason correctly explains the assertion. Therefore, the answer to the question is that both A and R are true, and R is the correct explanation for A.

### Final Answer:
Both the assertion (A) and the reason (R) are correct, and R is the correct explanation for A.

---