Assertion (A) Friedel - Crafts reaction benzene with n - propyl chloride on heating produce isopropyl benzene
Reason (R ) Benzene undergoes electrophilic substitution easily.

Options

A. If both Assertion and Reason are true and Reason is correct explanation of Assertion.
B. If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
C. If Assertion is true but Reason is false.
D. If both Assertion and Reason and false.

Answer

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Understanding the Assertion
The assertion states that the Friedel-Crafts reaction of benzene with n-propyl chloride produces isopropyl benzene.

- **Friedel-Crafts Reaction**: This is a type of electrophilic aromatic substitution where an alkyl group is introduced into an aromatic ring.
- **n-Propyl Chloride**: This is CH3-CH2-CH2-Cl. When it reacts with benzene in the presence of a Lewis acid (like AlCl3), it forms a carbocation.

### Step 2: Mechanism of the Reaction
1. **Formation of Electrophile**: n-Propyl chloride reacts with AlCl3 to form a propyl cation (CH3-CH2-CH2+).
2. **Electrophilic Attack**: The benzene ring, being rich in electron density, attacks the propyl cation, forming a non-aromatic cyclohexyl intermediate.
3. **Rearrangement**: The formed carbocation can undergo rearrangement (1,2-hydride shift) to form a more stable secondary carbocation (isopropyl cation, CH3-CH+-CH3).
4. **Restoration of Aromaticity**: The secondary carbocation then reacts with the benzene ring to form isopropyl benzene (C6H5-CH(CH3)2) and releases H+.

### Step 3: Conclusion about the Assertion
The assertion is **true** because the reaction does produce isopropyl benzene as the major product after rearrangement.

### Step 4: Understanding the Reason
The reason states that benzene undergoes electrophilic substitution easily.

- **Electrophilic Substitution**: This is a characteristic reaction of benzene due to its stable aromatic structure.
- The reason is also **true** because benzene is indeed reactive towards electrophiles.

### Step 5: Evaluating the Relationship
Now we need to determine if the reason correctly explains the assertion.

- While both the assertion and reason are true, the reason does not specifically explain why n-propyl chloride leads to isopropyl benzene. The formation of isopropyl benzene is due to the rearrangement of the carbocation, not just because benzene undergoes electrophilic substitution easily.

### Final Answer
Thus, the correct conclusion is:
- Both assertion and reason are true, but the reason is not the correct explanation of the assertion. Therefore, the answer is **Option B**.