Which of the following cannot reduce Fehling's solution ?

Options

A. Formic acid
B. Acetic acid
C. Formaldehyde
D. Acetaldehyde

Answer

To determine which of the following compounds cannot reduce Fehling's solution, we need to understand the nature of the compounds involved and the reaction that occurs with Fehling's solution.

### Step-by-Step Solution:

1. **Understanding Fehling's Solution**:
- Fehling's solution is a chemical test used to detect reducing sugars and aldehydes. It consists of two solutions: Fehling's A (copper(II) sulfate) and Fehling's B (a solution of sodium potassium tartrate in sodium hydroxide). When a reducing agent is present, the blue copper(II) ions (Cu²⁺) are reduced to red copper(I) oxide (Cu₂O).

2. **Identifying the Functional Groups**:
- To reduce Fehling's solution, a compound must contain a free aldehyde group (-CHO) or a reducing sugar. Compounds without this functional group will not be able to reduce the solution.

3. **Analyzing the Options**:
- **Option 1: Formic Acid (HCOOH)**:
- This compound has the aldehyde group (-CHO) and can reduce Fehling's solution.
- **Option 2: Acetic Acid (CH₃COOH)**:
- This compound does not have the aldehyde group; it is a carboxylic acid and cannot reduce Fehling's solution.
- **Option 3: Formaldehyde (HCHO)**:
- This compound has the aldehyde group and can reduce Fehling's solution.
- **Option 4: Acetaldehyde (CH₃CHO)**:
- This compound also has the aldehyde group and can reduce Fehling's solution.

4. **Conclusion**:
- The compound that cannot reduce Fehling's solution is **Acetic Acid (CH₃COOH)**, which is option 2.

### Final Answer:
**Acetic Acid (CH₃COOH) cannot reduce Fehling's solution.**