The maximum number of isomer for an alkene with the molecular formula `C_4H_8` is

Options

A. two
B. three
C. four
D. five

Answer

To determine the maximum number of isomers for an alkene with the molecular formula \( C_4H_8 \), we can follow these steps:

### Step 1: Identify the possible structural formulas
Alkenes are hydrocarbons that contain at least one carbon-carbon double bond (C=C). For \( C_4H_8 \), we can have different structural arrangements of the carbon atoms.

### Step 2: Determine the types of isomers
Isomers can be classified into two main types:
1. **Structural isomers**: Different connectivity of atoms.
2. **Geometric isomers (cis-trans isomerism)**: Different spatial arrangements of atoms due to the presence of a double bond.

### Step 3: List the structural isomers
For \( C_4H_8 \), the possible structural isomers include:
1. But-1-ene
2. But-2-ene (which has cis and trans forms)
3. Isobutylene (2-methylpropene)

### Step 4: Count the isomers
Now, let's count:
- **But-1-ene**: 1 isomer
- **But-2-ene**: 2 isomers (cis and trans)
- **Isobutylene (2-methylpropene)**: 1 isomer

Adding these up gives us:
- Total = 1 (But-1-ene) + 2 (But-2-ene) + 1 (Isobutylene) = 4 isomers

### Conclusion
The maximum number of isomers for an alkene with the molecular formula \( C_4H_8 \) is **4**.

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