Assertion : Benzaldehyde is less reactive towards nucleophilic addition than acetaldehyde.
Reason : In benzaldehydes, steric hindrance is more than in acetaldehyde.

Options

A. If both assertion and reason are correct and reason is correct explanation for assertion.
B. If both assertion and reason are correct and reason is not correct explanation for assertion.
C. If assertion is correct but reason is incorrect.
D. If assertion as well as reason are both incorrect.

Explanation

To solve the question regarding the reactivity of benzaldehyde and acetaldehyde towards nucleophilic addition, we can follow these steps:

### Step 1: Understand the Structures
- **Benzaldehyde** (C6H5CHO) consists of a benzene ring attached to a carbonyl group (C=O).
- **Acetaldehyde** (CH3CHO) consists of a carbonyl group attached to a methyl group (CH3).

### Step 2: Analyze the Electrophilicity
- In both compounds, the carbonyl carbon is electrophilic due to the partial positive charge created by the electronegativity of oxygen.
- The electrophilic carbon is the site for nucleophilic attack.

### Step 3: Consider Steric Hindrance
- **Benzaldehyde** has a bulky benzene ring, which creates steric hindrance around the carbonyl carbon.
- **Acetaldehyde**, on the other hand, has a smaller methyl group, resulting in less steric hindrance.

### Step 4: Compare Reactivity
- The greater steric hindrance in benzaldehyde makes it less reactive towards nucleophilic addition compared to acetaldehyde.
- Therefore, the assertion that benzaldehyde is less reactive towards nucleophilic addition than acetaldehyde is correct.

### Step 5: Evaluate the Reason
- The reason provided states that in benzaldehyde, steric hindrance is more than in acetaldehyde, which is also correct.
- This steric hindrance is indeed the reason for the lower reactivity of benzaldehyde.

### Conclusion
Both the assertion and the reason are correct, and the reason correctly explains the assertion.

### Final Answer
Both assertion and reason are correct, and the reason is the correct explanation for the assertion.

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