How many alkene on catalytic hydrogenation given isopentane as a product?

Options

A. 2
B. 3
C. 4
D. 5

Answer

To determine how many alkenes can yield isopentane upon catalytic hydrogenation, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Structure of Isopentane**:
- Isopentane (also known as 2-methylbutane) has the molecular formula C5H12. Its structure can be represented as:
```
CH3
|
CH3-CH-CH2-CH3
```

2. **Understand Catalytic Hydrogenation**:
- Catalytic hydrogenation involves the addition of hydrogen (H2) across a double bond (alkene) to form an alkane. Therefore, we need to find alkenes that can be converted to isopentane through this process.

3. **Identify Possible Alkenes**:
- We need to consider different alkenes that can be hydrogenated to form isopentane.
- The following three alkenes can be identified:
1. **Alkene 1**: 2-pentene (CH3-CH=CH-CH2-CH3)
2. **Alkene 2**: 3-pentene (CH3-CH2-CH=CH-CH3)
3. **Alkene 3**: 2-methyl-1-butene (CH2=C(CH3)-CH2-CH3)

4. **Draw the Structures of the Alkenes**:
- **Alkene 1**:
```
CH3
|
CH3-CH=CH-CH2-CH3
```
- **Alkene 2**:
```
CH3-CH2-CH=CH-CH3
```
- **Alkene 3**:
```
CH2
|
CH3-C=CH2
|
CH2-CH3
```

5. **Conclusion**:
- All three alkenes can be hydrogenated to yield isopentane. Therefore, the answer to the question is that there are **three alkenes** that can produce isopentane upon catalytic hydrogenation.

### Final Answer:
**Three alkenes can yield isopentane upon catalytic hydrogenation.**