The alkane which has only `1^(@) H` atoms is:

Options

A. Neopentane
B. Isopentane
C. Pentane
D. 2,2-Dimethy1 butane

Explanation

To determine the alkane that has only one degree hydrogen atoms, we need to understand what "one degree hydrogen" means. A one degree hydrogen atom is a hydrogen atom that is attached to a carbon atom, which is only connected to one other carbon atom.

### Step-by-Step Solution:

1. **Understand the Definition of One Degree Hydrogen:**
- A hydrogen atom attached to a carbon that is bonded to only one other carbon is called a primary (or one degree) hydrogen.
- If a hydrogen is attached to a carbon that is bonded to two other carbons, it is called a secondary (or two degree) hydrogen.

2. **Identify the Given Options:**
- The options provided are:
- A) Neopentane
- B) Isopentane
- C) Pentane
- D) 2,2-Dimethylbutane

3. **Analyze Each Option:**
- **Option A: Neopentane**
- Structure: C5H12
- All carbons in neopentane are bonded to only one other carbon, meaning all attached hydrogens are primary (one degree).
- Conclusion: All hydrogens are one degree hydrogens.

- **Option B: Isopentane**
- Structure: C5H12
- Contains a branched structure where some hydrogens are attached to carbons that are bonded to two other carbons.
- Conclusion: Not all hydrogens are one degree.

- **Option C: Pentane**
- Structure: C5H12
- Similar to isopentane, some hydrogens are attached to secondary carbons.
- Conclusion: Not all hydrogens are one degree.

- **Option D: 2,2-Dimethylbutane**
- Structure: C6H14
- Contains branching, leading to some hydrogens being attached to secondary carbons.
- Conclusion: Not all hydrogens are one degree.

4. **Final Conclusion:**
- After analyzing all options, the only alkane that has only one degree hydrogen atoms is **Neopentane** (Option A).

### Final Answer:
The alkane which has only `1^(@) H` atoms is **Neopentane**.