`C_(4)H_(8)O_(2)` represents :-

Options

A. An acid only
B. An ester only
C. An ketone only
D. An acid and an ester also

Answer

To determine what the molecular formula \( C_4H_8O_2 \) represents, we will analyze the possibilities of it being an acid, ester, or ketone.

### Step 1: Analyze the Acid Structure
1. **Definition**: An acid typically has the functional group -COOH (carboxylic acid).
2. **Structure**: For \( C_4H_8O_2 \):
- The structure can be represented as \( R-COOH \).
- We need to ensure we have 4 carbon atoms in total.
3. **Construction**:
- Start with the carboxylic group: \( -COOH \) (1 carbon).
- Add 3 more carbon atoms to the structure: \( CH_3-CH_2-COOH \).
- Count the hydrogens:
- The carboxylic group contributes 1 hydrogen.
- The 3 carbon atoms can be arranged to give a total of 8 hydrogens.
4. **Conclusion**: Therefore, \( C_4H_8O_2 \) can exist as an acid.

### Step 2: Analyze the Ester Structure
1. **Definition**: An ester has the functional group \( RCOOR' \).
2. **Structure**: For \( C_4H_8O_2 \):
- The structure can be represented as \( RCOOR' \).
- We need to ensure we have 4 carbon atoms in total.
3. **Construction**:
- Start with the carbonyl group: \( RCO \) (1 carbon).
- Add another carbon connected to the oxygen: \( R-O-R' \).
- The remaining carbon can be added to either \( R \) or \( R' \).
4. **Count the Hydrogens**:
- The structure can be \( CH_3COOCH_3 \) (methyl acetate).
- This gives a total of 8 hydrogens.
5. **Conclusion**: Therefore, \( C_4H_8O_2 \) can exist as an ester.

### Step 3: Analyze the Ketone Structure
1. **Definition**: A ketone has the functional group \( RC(=O)R' \).
2. **Structure**: For \( C_4H_8O_2 \):
- The structure can be represented as \( R-C(=O)-R' \).
- We need to ensure we have 4 carbon atoms in total.
3. **Construction**:
- Start with the carbonyl group: \( C(=O) \) (1 carbon).
- Add 2 more carbons to the sides of the carbonyl.
4. **Count the Hydrogens**:
- The structure can be \( CH_3COCH_2CH_3 \).
- This gives a total of 6 hydrogens, which is insufficient.
5. **Conclusion**: Therefore, \( C_4H_8O_2 \) cannot exist as a ketone.

### Final Conclusion
After analyzing all three possibilities:
- **Acid**: Exists
- **Ester**: Exists
- **Ketone**: Does not exist

Thus, \( C_4H_8O_2 \) can represent both an acid and an ester.

### Answer
The correct answer is that \( C_4H_8O_2 \) represents both an acid and an ester.

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