`C_(5)H_(10)O` is carbonyl compound. The number of structural isomers possible for this molecular formula are

Options

A. 5
B. 8
C. 6
D. 7

Answer

To determine the number of structural isomers for the carbonyl compound with the molecular formula \( C_5H_{10}O \), we need to consider both aldehydes and ketones, as the carbonyl group (C=O) can be present in either of these functional groups.

### Step-by-Step Solution:

1. **Identify the Functional Groups**:
- The carbonyl compound can either be an aldehyde or a ketone. Aldehydes have the carbonyl group at the end of the carbon chain, while ketones have it within the carbon chain.

2. **Count Aldehyde Isomers**:
- For aldehydes, the general structure is \( RCHO \).
- The longest carbon chain for an aldehyde with 5 carbons is pentanal.
- We can also create isomers by branching the carbon chain:
- **Pentanal** (straight chain)
- **2-Methylbutanal** (branching at the second carbon)
- **3-Methylbutanal** (branching at the third carbon)
- **2,2-Dimethylbutanal** (two methyl groups at the second carbon)
- Total aldehyde isomers = 4.

3. **Count Ketone Isomers**:
- For ketones, the general structure is \( RC(=O)R' \).
- The longest carbon chain for a ketone with 5 carbons can be either pentan-2-one or pentan-3-one:
- **Pentan-2-one** (carbonyl on the second carbon)
- **Pentan-3-one** (carbonyl on the third carbon)
- **3-Methylbutan-2-one** (branching with a methyl group on the 3rd carbon)
- Total ketone isomers = 3.

4. **Calculate Total Structural Isomers**:
- Total structural isomers = Number of aldehyde isomers + Number of ketone isomers
- Total = 4 (aldehydes) + 3 (ketones) = 7.

### Final Answer:
The total number of structural isomers possible for the molecular formula \( C_5H_{10}O \) is **7**.

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