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 determine the correctness of the assertion and reason provided in the question, we need to analyze both statements carefully.

### Step 1: Analyze the Assertion
The assertion states that "Ozonolysis of benzene gives ethanal."

- Ozonolysis is a reaction where ozone (O3) reacts with alkenes or alkynes to form carbonyl compounds (aldehydes or ketones).
- Benzene (C6H6) is an aromatic compound with a stable structure due to resonance.
- When benzene undergoes ozonolysis, it does not directly yield ethanal (acetaldehyde, CH3CHO). Instead, ozonolysis of benzene typically leads to the formation of various carbonyl compounds, but not specifically ethanal.

**Conclusion for Assertion:** The assertion is **incorrect**.

### Step 2: Analyze the Reason
The reason states that "Benzene is an antiaromatic compound."

- Benzene has a planar structure and contains 6 π electrons.
- According to Huckel's rule, a compound is aromatic if it has (4n + 2) π electrons, where n is a non-negative integer. For benzene, n = 1, thus it has 6 π electrons (4(1) + 2 = 6).
- This means benzene is **aromatic**, not antiaromatic. Antiaromatic compounds typically have 4n π electrons, which is not the case for benzene.

**Conclusion for Reason:** The reason is also **incorrect**.

### Final Conclusion
Both the assertion and the reason are incorrect. Therefore, the correct option is that neither the assertion nor the reason is true.