Write the structural isomers of an alkene having M.F. `C_4H_8`. How can you distinguish between them ?

Explanation

To find the structural isomers of the alkene with the molecular formula C4H8, we can follow these steps:

### Step 1: Identify the possible structural isomers
The molecular formula C4H8 indicates that we have an alkene, which contains at least one double bond. The structural isomers can be categorized based on the position of the double bond and the arrangement of carbon atoms.

1. **But-1-ene (CH2=CH-CH2-CH3)**: The double bond is between the first and second carbon atoms.
2. **But-2-ene (CH3-CH=CH-CH3)**: The double bond is between the second and third carbon atoms. This can exist in two geometric forms:
- **Cis-but-2-ene**: The two methyl groups (CH3) are on the same side of the double bond.
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