A : Ozonolysis of benzene gives ethanal.
R : Benzene is an antiaromatic compound.

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

### Step 1: Analyze the Assertion (A)
**Assertion (A): Ozonolysis of benzene gives ethanal.**

- Ozonolysis is a reaction typically used for alkenes, where ozone reacts with a double bond to form ozonides, which can then be reduced to carbonyl compounds (aldehydes or ketones).
- Benzene, however, is an aromatic compound with a stable structure due to resonance and does not undergo ozonolysis in the same way as alkenes.
- When considering the ozonolysis of benzene, it does not yield ethanal (acetaldehyde). Instead, the ozonolysis of benzene would typically lead to different products, such as carbonyl compounds, but not specifically ethanal.

**Conclusion for Assertion (A): False.**

### Step 2: Analyze the Reason (R)
**Reason (R): Benzene is an antiaromatic compound.**

- Benzene is a well-known aromatic compound, not antiaromatic. Aromatic compounds are characterized by having 4n + 2 π electrons (where n is a non-negative integer), which benzene satisfies with its 6 π electrons (n=1).
- Anti-aromatic compounds, on the other hand, have 4n π electrons and are generally unstable. Benzene's stability and aromaticity come from its cyclic structure and complete conjugation.

**Conclusion for Reason (R): False.**

### Step 3: Final Conclusion
Both the assertion and the reason are false. Therefore, the correct answer is that both A and R are false.

### Summary of the Solution:
1. **Assertion (A)** is false because ozonolysis of benzene does not yield ethanal.
2. **Reason (R)** is false because benzene is an aromatic compound, not antiaromatic.
3. Therefore, both A and R are false.