A: Pyrrole is less basic than pyridine.
R: Lone pair electron of nitrogen in pyrrole participate in conjugation to gain aromatic character.

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 analyze the assertion and reason provided in the question, we will follow these steps:

### Step 1: Understand the Assertion
The assertion states that "Pyrrole is less basic than pyridine."

**Explanation**:
- Pyrrole (C4H4NH) is a five-membered ring compound containing nitrogen, where the nitrogen atom has a lone pair of electrons.
- Pyridine (C5H5N) is a six-membered ring compound that contains nitrogen, where the nitrogen atom is sp2 hybridized and has a lone pair that is not involved in the aromatic system.

### Step 2: Understand the Reason
The reason states that "The lone pair electron of nitrogen in pyrrole participates in conjugation to gain aromatic character."

**Explanation**:
- In pyrrole, the lone pair of electrons on the nitrogen atom is involved in the aromatic system of the ring. This means that the lone pair is not available for protonation (donation) and thus decreases the basicity of pyrrole.
- In contrast, in pyridine, the lone pair on nitrogen is not involved in the aromatic system, making it available for donation, thus increasing its basicity.

### Step 3: Compare Basicity
- Pyrrole's lone pair is engaged in the aromatic system, making it less available for bonding with protons, thus it is less basic.
- Pyridine's lone pair is free and can easily accept protons, making it more basic.

### Conclusion
- The assertion is **true**: Pyrrole is indeed less basic than pyridine.
- The reason is also **true**: The lone pair on nitrogen in pyrrole does participate in conjugation, contributing to its aromatic character.

### Final Answer
Both the assertion and the reason are true, and the reason correctly explains the assertion.

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