Question

Which one of the following is an aromatic compound?

• A. A
• B. B
• C. C
• D. D

Hint:

Aromatic compounds must have a conjugated system and satisfy the \( 4n + 2 \) \(\pi\)-electron rule. The most common example is benzene, which is shown in Option A.

Answer 1

The Correct Option is A

Step 1: Understanding Aromatic Compounds.
Aromatic compounds follow the Huckel rule, which states that for a compound to be aromatic, it must:
Be cyclic,
Be planar,
Contain a conjugated system of alternating single and double bonds (alternating bonds are a characteristic of a conjugated system),
Contain a total number of π-electrons that follow the formula \( 4n + 2 \), where \( n \) is a non-negative integer (this is called the Huckel criterion for aromaticity).
Step 2: Analyze each option.
Option (1) A: This compound is a six-membered carbon ring with conjugated double bonds and follows the Huckel rule with 6 π-electrons, which satisfy the \( 4n + 2 \) rule (for \( n = 1 \)). Therefore, A is aromatic.
Option (2) B: This compound has a positive charge on one carbon and a negative charge on another, indicating that it is not a simple aromatic ring with conjugated bonds. Hence, it is not aromatic.
Option (3) C: This compound has no conjugation and does not satisfy the Huckel rule, so it is not aromatic.
Option (4) D: This is a simple six-membered ring with no alternating single and double bonds. This structure does not satisfy the Huckel criterion for aromaticity.
Step 3: Conclusion.
The correct aromatic compound is Option A.