Which of the following has only `1^(@)` and `2^(@)C` atoms?

Options

A. 2-Methy1 butane
B. Butane
C. 2,2-Dimethy1 butane
D. 2,2,3,3-Tetramethy1 pentance

Explanation

To determine which of the given compounds contains only primary and secondary carbon atoms, we need to analyze the carbon atoms in each compound. Here’s a step-by-step solution:

### Step 1: Understand Carbon Types
- **Primary Carbon (1°)**: A carbon atom bonded to only one other carbon atom.
- **Secondary Carbon (2°)**: A carbon atom bonded to two other carbon atoms.
- **Tertiary Carbon (3°)**: A carbon atom bonded to three other carbon atoms.
- **Quaternary Carbon (4°)**: A carbon atom bonded to four other carbon atoms.

### Step 2: Analyze Each Compound
1. **2-Methylbutane**:
- Structure:
- 1°: 3 carbons at the ends of the chain.
- 2°: 2 carbons in the middle.
- Conclusion: Contains both primary and secondary carbons.

2. **Butane**:
- Structure:
- 1°: 2 terminal carbons.
- 2°: 2 middle carbons.
- Conclusion: Contains only primary and secondary carbons.

3. **2,2-Dimethylbutane**:
- Structure:
- 1°: 3 terminal carbons.
- 2°: 1 carbon in the middle.
- 3°: 2 carbons are tertiary.
- Conclusion: Contains tertiary carbons.

4. **2,2,3,3-Tetramethylpentane**:
- Structure:
- 1°: 4 terminal carbons.
- 2°: 0 middle carbons.
- 3°: 2 carbons are tertiary.
- Conclusion: Contains tertiary carbons.

### Step 3: Identify the Compound with Only 1° and 2° Carbons
- After analyzing all the compounds, we find that **Butane** is the only compound that contains only primary and secondary carbon atoms.

### Final Answer:
The compound that has only primary and secondary carbon atoms is **Butane**.

---