Write structures of all the alkenes which on hydrogenation give 2-methylbutane.

Explanation

To find all the alkenes that can be hydrogenated to yield 2-methylbutane, we first need to understand the structure of 2-methylbutane itself. The molecular formula for 2-methylbutane is C5H12, which indicates it is a saturated hydrocarbon.

### Step-by-Step Solution:

1. **Identify the Structure of 2-Methylbutane**:
- The structure of 2-methylbutane can be represented as:
```
CH3
|
CH3-CH-CH2-CH3
```
- This shows that 2-methylbutane has a branched structure with a methyl group (CH3) attached to the second carbon of a butane chain.

2. **Determine Possible Alkenes**:
- To find the alkenes that can be hydrogenated to form 2-methylbutane, we need to place a double bond in various positions of the carbon chain that will allow for the addition of hydrogen atoms to convert them into 2-methylbutane.

3. **First Alkene Structure**:
- One possible alkene is:
```
CH2=CH-CH(CH3)-CH3
```
- This alkene has a double bond between the first and second carbon atoms.

4. **Second Alkene Structure**:
- Another possible alkene is:
```
CH3-CH=CH-CH2-CH3
```
- Here, the double bond is between the second and third carbon atoms.

5. **Third Alkene Structure**:
- A third possible alkene is:
```
CH3-CH(CH3)-CH=CH2
```
- In this case, the double bond is between the third and fourth carbon atoms.

6. **Conclusion**:
- The three alkenes that can be hydrogenated to yield 2-methylbutane are:
1. CH2=CH-CH(CH3)-CH3
2. CH3-CH=CH-CH2-CH3
3. CH3-CH(CH3)-CH=CH2