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

Explanation

To solve the problem of identifying all the alkenes that can be hydrogenated to yield 2-methylbutane, we will follow these steps:

### Step 1: Understand the Product
The product we need to obtain is 2-methylbutane. This is a branched alkane with the following structure:

```
CH3
|
CH3-CH-CH2-CH3
|
CH3
```

### Step 2: Identify Possible Alkenes
To find the alkenes that can be hydrogenated to form 2-methylbutane, we need to consider where we can place a double bond in the structure of the alkenes. The double bond can be placed in different positions in the carbon chain.

### Step 3: Write Structures of Alkenes
1. **3-Methylbut-1-ene**:
- Structure:
```
CH2=CH-CH(CH3)-CH3
```

2. **3-Methylbut-2-ene**:
- Structure:
```
CH3-CH=CH(CH3)-CH3
```

3. **2-Methylbut-1-ene**:
- Structure:
```
CH2=CH-CH2-CH(CH3)-CH3
```

### Step 4: Verify Hydrogenation
When these alkenes undergo hydrogenation (addition of hydrogen across the double bond), they will yield 2-methylbutane:

- **3-Methylbut-1-ene** + H2 → 2-Methylbutane
- **3-Methylbut-2-ene** + H2 → 2-Methylbutane
- **2-Methylbut-1-ene** + H2 → 2-Methylbutane

### Final Answer
The alkenes that can be hydrogenated to give 2-methylbutane are:
1. 3-Methylbut-1-ene
2. 3-Methylbut-2-ene
3. 2-Methylbut-1-ene