All of the following are four carbon compounds except

Options

A. Malic acid
B. Succinic acid
C. Pyruvic acid
D. Oxaloacetic acid

Answer

To solve the question "All of the following are four carbon compounds except," we will analyze each of the given compounds one by one to determine their chemical formulas and the number of carbon atoms they contain.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds listed in the question are:
- Malic acid
- Succinic acid
- Pyruvic acid
- Oxaloacetic acid

2. **Analyze Malic Acid**:
- **Chemical Formula**: C₄H₆O₅
- **Number of Carbon Atoms**: 4
- **Conclusion**: Malic acid is a four-carbon compound.

3. **Analyze Succinic Acid**:
- **Chemical Formula**: C₄H₆O₄
- **Number of Carbon Atoms**: 4
- **Conclusion**: Succinic acid is also a four-carbon compound.

4. **Analyze Pyruvic Acid**:
- **Chemical Formula**: C₃H₄O₃
- **Number of Carbon Atoms**: 3
- **Conclusion**: Pyruvic acid is NOT a four-carbon compound; it is a three-carbon compound.

5. **Analyze Oxaloacetic Acid**:
- **Chemical Formula**: C₄H₄O₅
- **Number of Carbon Atoms**: 4
- **Conclusion**: Oxaloacetic acid is a four-carbon compound.

6. **Final Conclusion**:
- Among the compounds analyzed, malic acid, succinic acid, and oxaloacetic acid are all four-carbon compounds, while pyruvic acid is a three-carbon compound. Therefore, the answer to the question is **pyruvic acid**.

### Final Answer:
**Pyruvic acid** is the exception as it is not a four-carbon compound.

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