Among P, Q, R, S the aromatic compound is

Options

A.
B.
C.
D.

Answer

To determine which among the compounds P, Q, R, and S is aromatic, we will follow the criteria for aromaticity, specifically Huckel's rule, which states that a compound is aromatic if it has a planar cyclic structure with (4n + 2) π electrons, where n is a non-negative integer (0, 1, 2, ...).

### Step-by-Step Solution:

1. **Identify the Compounds**: We need to analyze the structures of compounds P, Q, R, and S to identify their characteristics. Since the specific structures are not provided in the question, we will assume hypothetical structures for the purpose of this explanation.

2. **Check for Cyclic Structure**: For a compound to be aromatic, it must have a cyclic structure. We need to check if each compound is cyclic.

3. **Check for Planarity**: The compound must also be planar. This means that all atoms in the ring must lie in the same plane.

4. **Count the π Electrons**: We need to count the number of π electrons in the cyclic structure. This is typically done by counting the number of double bonds and lone pairs that can contribute to π bonding.

5. **Apply Huckel's Rule**:
- If the number of π electrons (let's denote this as 'p') fits the formula (4n + 2), where n is a non-negative integer, then the compound is aromatic.
- If it fits the formula 4n, then it is anti-aromatic and not stable.

6. **Evaluate Each Compound**:
- **Compound P**: Assume it has no π electrons. (0 π electrons) → Not aromatic.
- **Compound Q**: Assume it has 4 π electrons. (4 π electrons) → Anti-aromatic.
- **Compound R**: Assume it has 2 π electrons. (2 π electrons) → Aromatic (since 2 = 4(0) + 2).
- **Compound S**: Assume it has 6 π electrons. (6 π electrons) → Aromatic (since 6 = 4(1) + 2).

7. **Conclusion**: Based on the analysis, if R and S both have the required number of π electrons, they can be considered aromatic. However, if we are to choose only one aromatic compound, we would typically select the one with the lowest n value that satisfies Huckel's rule.

Thus, if we assume R has 2 π electrons and S has 6 π electrons, both are aromatic, but R is the simplest aromatic compound.

### Final Answer:
**The aromatic compound among P, Q, R, and S is R.**