The structue of alkane or cycloalkane with molecular formula `C_(8)H_(18)` that has only `1^(@)` H atoms is:

Options

A. (a) 2,2,3,3-Tetramethylbutane
B. (b) 2,2,3-Trimethylpentane
C. (c) 2,2,4-Trimethylpentane
D. (d) 2,3,3-Trimethylpentane

Explanation

To determine the structure of an alkane or cycloalkane with the molecular formula \( C_8H_{18} \) that has only one degree of hydrogen atoms, we can follow these steps:

### Step 1: Understand the concept of degree of hydrogen atoms
- A primary (1°) hydrogen atom is attached to a primary carbon atom, which is bonded to only one other carbon atom.
- A secondary (2°) hydrogen atom is attached to a secondary carbon atom, which is bonded to two other carbon atoms.
- A tertiary (3°) hydrogen atom is attached to a tertiary carbon atom, which is bonded to three other carbon atoms.
- A quaternary (4°) carbon atom has no hydrogen atoms because it is bonded to four other carbon atoms.

### Step 2: Identify possible structures for \( C_8H_{18} \)
- The molecular formula \( C_8H_{18} \) suggests that we are dealing with an alkane, which is a saturated hydrocarbon.
- We can draw various structural isomers of \( C_8H_{18} \) and analyze them for the number of primary hydrogen atoms.

### Step 3: Analyze each structure
1. **2,2,3,3-Tetramethylbutane**:
- Structure:
```
CH3
|
CH3-C-CH3
|
CH3
```
- Analysis: This structure has four tertiary carbons and no primary hydrogens. **Incorrect**.

2. **2,2,3-Trimethylpentane**:
- Structure:
```
CH3
|
CH3-C-CH2-CH3
|
CH3
```
- Analysis: This structure has both primary and secondary hydrogens. **Incorrect**.

3. **2,2,4-Trimethylpentane**:
- Structure:
```
CH3
|
CH3-C-CH2-CH3
|
CH3
```
- Analysis: Similar to the previous structure, it contains primary, secondary, and tertiary hydrogens. **Incorrect**.

4. **2,3,3-Trimethylpentane**:
- Structure:
```
CH3
|
CH3-C-CH-CH3
|
CH3
```
- Analysis: This structure also contains primary, secondary, and tertiary hydrogens. **Incorrect**.

5. **2,2-Dimethylbutane**:
- Structure:
```
CH3
|
CH3-C-CH2-CH3
|
CH3
```
- Analysis: This structure contains primary and secondary hydrogens. **Incorrect**.

### Step 4: Identify the correct structure
After analyzing the various structures, the only structure that contains only primary hydrogen atoms is **2,2,3,3-Tetramethylbutane**.

### Conclusion
The structure of the alkane or cycloalkane with the molecular formula \( C_8H_{18} \) that has only one degree of hydrogen atoms is **2,2,3,3-Tetramethylbutane**.

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