Which does not react with Fehling's solution?

Options

A. Acetaldehyde
B. Benzaldehyde
C. Glucose
D. Formic acid

Answer

To determine which compound does not react with Fehling's solution, we need to analyze the nature of the compounds in question. Fehling's solution is used to distinguish between aldehydes and ketones, as well as to differentiate between aliphatic and aromatic aldehydes.

### Step-by-Step Solution:

1. **Understanding Fehling's Solution**:
- Fehling's solution is a chemical reagent used to test for the presence of aldehydes. It consists of two solutions: Fehling's A (copper(II) sulfate) and Fehling's B (alkaline tartrate). When mixed and heated with an aldehyde, a red precipitate of copper(I) oxide (Cu2O) is formed.

2. **Identifying the Types of Compounds**:
- The question involves identifying which compound does not react with Fehling's solution. The compounds mentioned include:
- Acetaldehyde (an aliphatic aldehyde)
- Benzaldehyde (an aromatic aldehyde)
- Glucose (an aldose sugar)
- Formic acid (a carboxylic acid)

3. **Analyzing Each Compound**:
- **Acetaldehyde (CH3CHO)**: This is an aliphatic aldehyde and will react with Fehling's solution, producing a red precipitate.
- **Benzaldehyde (C6H5CHO)**: This is an aromatic aldehyde. Aromatic aldehydes do not react with Fehling's solution, so it will not produce a red precipitate.
- **Glucose (C6H12O6)**: Although glucose is a sugar, it has an aldehyde group and will react with Fehling's solution, producing a red precipitate.
- **Formic Acid (HCOOH)**: This is a carboxylic acid and does not have the aldehyde functional group that would allow it to react with Fehling's solution.

4. **Conclusion**:
- Among the compounds listed, benzaldehyde is the one that does not react with Fehling's solution because it is an aromatic aldehyde. Formic acid, while not reacting with Fehling's solution, is not the primary focus of the question as it is not an aldehyde.

### Final Answer:
The compound that does not react with Fehling's solution is **Benzaldehyde**.