The compound which has one isopropyl group is
2, 2, 3, 3-tetramethylpentane
2,2-dimethylpentane
2, 2, 3-trimethylpentane
2-methylpentane.

Options

A. 2, 2, 3, 3-tetramethylpentane
B. 2,2-dimethylpentane
C. 2, 2, 3-trimethylpentane
D. 2-methylpentane.

Explanation

To determine which compound has one isopropyl group, we will analyze each of the given compounds by drawing their structures and identifying the presence of isopropyl groups.

### Step 1: Draw the structure of 2,2,3,3-tetramethylpentane
- The name indicates a pentane backbone with four methyl groups at positions 2 and 3.
- The structure is as follows:
```
CH3
|
CH3--C--CH--C--CH3
| |
CH3 CH3
```
- This compound has no isopropyl groups.

### Step 2: Draw the structure of 2,2-dimethylpentane
- The name indicates a pentane backbone with two methyl groups at position 2.
- The structure is as follows:
```
CH3
|
CH3--C--CH2--C--CH3
|
CH3
```
- This compound also has no isopropyl groups.

### Step 3: Draw the structure of 2,2,3-trimethylpentane
- The name indicates a pentane backbone with three methyl groups at positions 2 and 3.
- The structure is as follows:
```
CH3
|
CH3--C--CH--C--CH3
| |
CH3 CH3
```
- This compound has no isopropyl groups.

### Step 4: Draw the structure of 2-methylpentane
- The name indicates a pentane backbone with one methyl group at position 2.
- The structure is as follows:
```
CH3
|
CH3--C--CH2--C--CH3
|
CH2
```
- This compound has a branched structure that can be recognized as having one isopropyl group.

### Conclusion
After analyzing all the compounds, the only compound that contains one isopropyl group is **2-methylpentane**.

### Final Answer
The compound which has one isopropyl group is **2-methylpentane**.

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