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 question, we need to analyze the assertion (A) and the reason (R) given:

**Assertion (A):** Diamagnetism is exhibited by all substances.
**Reason (R):** Diamagnetism is due to paired electrons.

### Step-by-Step Solution:

1. **Understanding Diamagnetism:**
- Diamagnetism is a type of magnetism that is exhibited by all materials. It is characterized by the material's weak repulsion to magnetic fields.

2. **Analyzing the Assertion (A):**
- The assertion states that "Diamagnetism is exhibited by all substances." This is true because all materials have electrons, and the motion of these electrons in their orbits creates a magnetic field. However, the effect is very weak and often goes unnoticed in materials that exhibit stronger forms of magnetism (like ferromagnetism or paramagnetism).

3. **Understanding the Reason (R):**
- The reason states that "Diamagnetism is due to paired electrons." This is also true. In diamagnetic materials, all the electrons are paired, meaning that their magnetic moments cancel each other out, resulting in no net magnetic moment.

4. **Combining the Assertion and Reason:**
- Since both the assertion and the reason are true, and the reason correctly explains the assertion, we conclude that both statements are correct.

5. **Final Conclusion:**
- Therefore, the answer to the question is that both the assertion and the reason are true, and the reason explains the assertion.

### Answer:
Both Assertion (A) and Reason (R) are true, and R explains A correctly.