A: Diamagnetism is exhibited by all the substances.
R: Diamagentism is due to paired electrons.

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 assertion and reason question regarding diamagnetism, we can break it down into clear steps:

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Diamagnetism is exhibited by all substances."
- This means that every material, regardless of its other magnetic properties, will show some level of diamagnetism.

2. **Analyzing the Reason**:
- The reason provided is that "Diamagnetism is due to paired electrons."
- In diamagnetic materials, all electrons are paired, which results in no net magnetic moment. This is a fundamental characteristic of diamagnetic substances.

3. **Evaluating the Assertion**:
- While it is true that all substances exhibit diamagnetism, the strength of this property can vary significantly. In materials that exhibit stronger magnetic properties (like ferromagnetic materials), the diamagnetic effect can be overshadowed and may not be observable.

4. **Evaluating the Reason**:
- The reason is also true. The presence of paired electrons in diamagnetic materials leads to the cancellation of magnetic moments, resulting in no net magnetic field.

5. **Conclusion**:
- Both the assertion and the reason are true. Furthermore, the reason correctly explains the assertion because the paired electrons in diamagnetic materials are indeed the reason for their diamagnetic behavior.

6. **Final Answer**:
- Therefore, the correct option is that both the assertion and the reason are true, and the reason is the correct explanation of the assertion.