Which of the following compounds can yield only one monochlorinated product upon free radical chlorination?

Options

A. 2,2-Dimethylopropane
B. 2-Methylpropane
C. 2-Methybutane
D. n-Butane

Explanation

To determine which compound can yield only one monochlorinated product upon free radical chlorination, we need to analyze the types of hydrogen atoms present in each compound. The key is that a compound will yield only one monochlorinated product if all the hydrogen atoms are of the same type (i.e., they are all equivalent).

### Step-by-Step Solution:

1. **Identify the Compounds**: We have four options to consider. Let's denote them as follows:
- Option 1: 2,2-dimethylpropane
- Option 2: 2-methylpropane
- Option 3: 2-methylbutane
- Option 4: n-butane

2. **Analyze Option 1 - 2,2-Dimethylpropane**:
- Structure:
```
CH3
|
CH3 - C - CH3
|
CH3
```
- This compound has a central carbon atom bonded to three methyl groups and one hydrogen. All the hydrogen atoms are equivalent.
- Upon chlorination, regardless of where the chlorine radical attacks, it will yield the same product (1-chloro-2,2-dimethylpropane).
- **Conclusion**: This compound will yield only one monochlorinated product.

3. **Analyze Option 2 - 2-Methylpropane**:
- Structure:
```
CH3
|
CH3 - C - CH2 - CH3
|
CH3
```
- This compound has different types of hydrogen atoms (primary and secondary).
- Chlorination can yield multiple products due to the presence of different types of hydrogens.
- **Conclusion**: This compound will yield more than one monochlorinated product.

4. **Analyze Option 3 - 2-Methylbutane**:
- Structure:
```
CH3
|
CH3 - C - CH2 - CH3
|
CH2 - CH3
```
- Similar to 2-methylpropane, this compound has different types of hydrogen atoms (primary and secondary).
- Chlorination can yield multiple products.
- **Conclusion**: This compound will yield more than one monochlorinated product.

5. **Analyze Option 4 - n-Butane**:
- Structure:
```
CH3 - CH2 - CH2 - CH3
```
- This compound has different types of hydrogen atoms (primary).
- Chlorination can yield multiple products due to the presence of different types of hydrogens.
- **Conclusion**: This compound will yield more than one monochlorinated product.

6. **Final Conclusion**:
- The only compound that yields only one monochlorinated product upon free radical chlorination is **Option 1: 2,2-dimethylpropane**.

### Answer:
**Option 1: 2,2-dimethylpropane** yields only one monochlorinated product upon free radical chlorination.