A: Arene diazonium salts are more stable than alkane diazonlum salts.
R: Positive charge is dispersed on ring in arene diazonium salts.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the reason 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 regarding the stability of arene diazonium salts compared to alkane diazonium salts, we will analyze the assertion (A) and reason (R) provided in the question.

### Step-by-Step Solution:

1. **Understanding Diazonium Salts**:
- Diazonium salts are compounds that contain a diazonium group (–N₂⁺) attached to a carbon atom. They can be derived from primary amines when treated with nitrous acid (HNO₂).

2. **Assertion (A)**: "Arene diazonium salts are more stable than alkane diazonium salts."
- Arene diazonium salts are formed from aromatic amines, while alkane diazonium salts are formed from aliphatic amines.
- It is known that arene diazonium salts are indeed more stable than their aliphatic counterparts.

3. **Reason (R)**: "Positive charge is dispersed on the ring in arene diazonium salts."
- In arene diazonium salts, the positive charge on the nitrogen can be delocalized over the aromatic ring due to resonance.
- This delocalization stabilizes the diazonium salt because the positive charge is not localized on a single atom but is spread over multiple atoms in the aromatic system.

4. **Resonance in Arene Diazonium Salts**:
- The aromatic ring has a system of π electrons that can participate in resonance. When the diazonium group is attached, the π electrons can shift, allowing the positive charge to be distributed across the ring.
- This resonance leads to multiple contributing structures, which enhances stability.

5. **Comparison with Alkane Diazonium Salts**:
- Alkane diazonium salts do not have the same resonance stabilization. The positive charge in these salts is localized on the nitrogen and does not benefit from delocalization, making them less stable.
- As a result, alkane diazonium salts are prone to decomposition, often yielding carbocations and nitrogen gas.

6. **Conclusion**:
- Both the assertion (A) and reason (R) are correct. Arene diazonium salts are more stable than alkane diazonium salts due to the resonance stabilization that disperses the positive charge over the aromatic ring.

### Final Answer:
Both the assertion (A) and reason (R) are correct, and the reason correctly explains the assertion.