Which sugar does not give benedict test?

Options

A. glucose
B. maltose
C. fructose
D. sucrose

Answer

**Step-by-Step Solution:**

1. **Understanding Benedict's Test**: Benedict's test is a qualitative test used to detect the presence of reducing sugars. It involves the use of an alkaline solution of copper sulfate, which reacts with reducing sugars to produce a color change.

2. **Identifying Reducing Sugars**: Reducing sugars are those that have a free aldehyde or ketone group. Common examples include glucose, maltose, and fructose. These sugars can reduce copper (II) ions in the Benedict's solution to form a colored precipitate.

3. **Analyzing Sucrose**: Sucrose is a disaccharide composed of one glucose molecule and one fructose molecule. In sucrose, the aldehyde group of glucose and the ketone group of fructose are involved in a glycosidic bond, which means they are not free to react with the Benedict's reagent.

4. **Conclusion**: Since sucrose does not have a free aldehyde or ketone group available for reaction, it does not give a positive result in the Benedict's test. Therefore, the sugar that does not give a Benedict's test is sucrose.

5. **Final Answer**: The sugar that does not give a Benedict's test is **sucrose**.

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