Which among the following is a non-planar molecule?

Options

A.
B.
C.
D.

Answer

To determine which among the given molecules is a non-planar molecule, we will analyze each option based on their hybridization and structural characteristics.

### Step-by-Step Solution:

1. **Identify the Molecules**: The question presents several molecules, including benzene, pyrrole, cyclohexane, and naphthalene. We need to analyze each one to determine if it is planar or non-planar.

2. **Analyze Benzene**:
- Benzene is a cyclic compound with the formula C₆H₆.
- Each carbon atom in benzene is sp² hybridized, which leads to a planar structure.
- Benzene follows Huckel's rule (4n + 2 π electrons) with 6 π electrons, confirming its aromaticity and planarity.
- **Conclusion**: Benzene is planar.

3. **Analyze Pyrrole**:
- Pyrrole is a five-membered ring with the formula C₄H₄NH.
- The nitrogen atom in pyrrole has a lone pair, but it is involved in delocalization, making the nitrogen effectively sp² hybridized.
- All carbon atoms are also sp² hybridized, leading to a planar structure.
- Pyrrole also follows Huckel's rule with 6 π electrons.
- **Conclusion**: Pyrrole is planar.

4. **Analyze Cyclohexane**:
- Cyclohexane is a six-membered ring with the formula C₆H₁₂.
- Each carbon atom is sp³ hybridized, which results in a tetrahedral geometry.
- The sp³ hybridization indicates that cyclohexane cannot be planar, as the bond angles are approximately 109.5°.
- **Conclusion**: Cyclohexane is non-planar.

5. **Analyze Naphthalene**:
- Naphthalene consists of two fused benzene rings (C₁₀H₈).
- Each carbon atom in naphthalene is sp² hybridized, leading to a planar structure.
- Naphthalene follows Huckel's rule with 10 π electrons.
- **Conclusion**: Naphthalene is planar.

6. **Final Conclusion**:
- Among the analyzed molecules, cyclohexane is the only non-planar molecule.
- Therefore, the correct answer is **Option C: Cyclohexane**.