Among the following the aromatic compound is

Options

A.
B.
C.
D.

Explanation

To determine which of the given compounds is aromatic, we will apply Huckel's rule. Huckel's rule states that for a compound to be classified as aromatic, it must satisfy the following criteria:

1. The compound must be planar.
2. The compound must have a certain number of delocalized π (pi) electrons, specifically following the formula \(4n + 2\), where \(n\) is a non-negative integer (0, 1, 2, 3, ...).

Now, let's analyze each part of the question step by step.

### Step 1: Analyze Part A
- **Planarity**: Check if the compound is planar. All the carbon atoms in part A are sp² hybridized, indicating that they are in a trigonal planar configuration. Thus, the compound is planar.
- **Count π Electrons**: There is 1 pi bond, which contributes 2 π electrons.
- **Check Huckel's Rule**:
\[ 4n + 2 = 2 \implies 4n = 0 \implies n = 0 \]
Since \(n = 0\) is acceptable, part A satisfies both criteria for aromaticity.

### Step 2: Analyze Part B
- **Planarity**: All carbon atoms are sp² hybridized, making the compound planar.
- **Count π Electrons**: There are 2 pi bonds, contributing 4 π electrons.
- **Check Huckel's Rule**:
\[ 4n + 2 = 4 \implies 4n = 2 \implies n = 0.5 \]
Since \(n = 0.5\) is not acceptable, part B does not satisfy the criteria for aromaticity.

### Step 3: Analyze Part C
- **Planarity**: All carbon atoms are sp² hybridized, indicating the compound is planar.
- **Count π Electrons**: There are 2 pi bonds, contributing 4 π electrons.
- **Check Huckel's Rule**:
\[ 4n + 2 = 4 \implies 4n = 2 \implies n = 0.5 \]
Since \(n = 0.5\) is not acceptable, part C does not satisfy the criteria for aromaticity.

### Step 4: Analyze Part D
- **Planarity**: In this part, one of the carbons is sp³ hybridized, which means the compound is not planar.
- **Count π Electrons**: The total number of π electrons is 4 (2 from the pi bonds and 2 from the negative charge).
- **Check Huckel's Rule**:
\[ 4n + 2 = 4 \implies 4n = 2 \implies n = 0.5 \]
Since the compound is not planar, it already fails the first criterion. Thus, part D is not aromatic.

### Conclusion
The only aromatic compound among the given options is **Part A**.

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