how many structural isomers are possible for `C_6H_14`?

Options

A. 4
B. 5
C. 6
D. 7

Answer

To determine how many structural isomers are possible for the molecular formula \( C_6H_{14} \), we will systematically identify all the possible structural isomers.

### Step-by-Step Solution:

1. **Identify the Molecular Formula**:
- The molecular formula \( C_6H_{14} \) indicates that we have a saturated hydrocarbon (alkane) with 6 carbon atoms and 14 hydrogen atoms.

2. **Determine the Longest Carbon Chain**:
- The longest continuous chain of carbon atoms can be 6, which gives us the straight-chain alkane known as **n-hexane**.

3. **Consider Branching**:
- We can create branched isomers by removing one or more hydrogen atoms from the longest chain and adding them to a branch.

4. **List Possible Isomers**:
- **n-Hexane**: The straight-chain structure (1).
- **2-Methylpentane**: A 5-carbon chain with a methyl group on the second carbon (2).
- **3-Methylpentane**: A 5-carbon chain with a methyl group on the third carbon (3).
- **2,2-Dimethylbutane**: A 4-carbon chain with two methyl groups on the second carbon (4).
- **2,3-Dimethylbutane**: A 4-carbon chain with one methyl group on the second carbon and another on the third carbon (5).

5. **Count the Isomers**:
- After listing all the structural isomers, we find that there are a total of **5 structural isomers** for \( C_6H_{14} \).

### Final Answer:
The total number of structural isomers for \( C_6H_{14} \) is **5**.

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