Reducing sugars like glucose in Fehling solution reduce

Options

A. `Fe^(++)` to `Fe^(+++)`
B. `Cu^(++)` to `Cu^(+)`
C. `Hg^(++)` to `Hg^(+)`
D. `Cu^(+)` to `Cu^(++)`

Answer

To solve the question about how reducing sugars like glucose react in Fehling's solution, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Reducing Sugars**:
- Reducing sugars are carbohydrates that can act as reducing agents. They contain free aldehyde or ketone groups that allow them to donate electrons.

2. **Identifying Glucose as a Reducing Sugar**:
- Glucose is a monosaccharide and is classified as a reducing sugar because it has a free aldehyde group in its structure.

3. **Fehling's Solution Composition**:
- Fehling's solution is a chemical reagent used to test for the presence of reducing sugars. It consists of two solutions: Fehling's A (copper(II) sulfate) and Fehling's B (alkaline tartrate solution).

4. **Reaction Mechanism**:
- When glucose is added to Fehling's solution, it reduces the copper(II) ions (Cu²⁺) present in the solution. The aldehyde group of glucose donates electrons to the copper ions.

5. **Reduction Process**:
- The copper(II) ions (Cu²⁺) are reduced to copper(I) ions (Cu⁺), which then precipitate out of the solution as copper(I) oxide (Cu₂O), resulting in a color change (usually a brick-red precipitate).

6. **Conclusion**:
- Therefore, the correct answer to the question is that reducing sugars like glucose in Fehling's solution reduce copper(II) ions (Cu²⁺) to copper(I) ions (Cu⁺).

### Final Answer:
Reducing sugars like glucose in Fehling's solution reduce Cu²⁺ (copper(II) ions) to Cu⁺ (copper(I) ions).

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