Which of the following compound shows negative Tollen's and Fehling's test (both) ?

Options

A. Formic acid
B. Formaldehyde
C. Benzaldehyde
D. Benzoic acid

Answer

To determine which compound shows negative Tollen's and Fehling's tests, we need to understand the nature of these tests and the functional groups present in the compounds given.

### Step-by-Step Solution:

1. **Understanding Tollen's and Fehling's Tests**:
- Tollen's test is used to detect aldehydes. Aldehydes generally give a positive result, while ketones do not.
- Fehling's test is similar; it is also used to detect aldehydes, particularly those with an alpha-hydrogen. Aldehydes with no alpha-hydrogens will give a negative result.

2. **Analyzing the Compounds**:
- **Formic Acid (HCOOH)**: This is a carboxylic acid but can be considered as an aldehyde (HCHO) in its structure. It gives a positive Tollen's test.
- **Formaldehyde (HCHO)**: This is a simple aldehyde and will give a positive result for both Tollen's and Fehling's tests.
- **Benzaldehyde (C6H5CHO)**: This is an aromatic aldehyde. It gives a positive Tollen's test but a negative Fehling's test because it has no alpha-hydrogens.
- **Benzoic Acid (C6H5COOH)**: This is a carboxylic acid and does not have an aldehyde functional group. Therefore, it will give negative results for both Tollen's and Fehling's tests.

3. **Conclusion**:
- Among the compounds analyzed, only **Benzoic Acid (C6H5COOH)** shows negative results for both Tollen's and Fehling's tests.

### Final Answer:
The compound that shows negative Tollen's and Fehling's tests is **Benzoic Acid (C6H5COOH)**.