Question

Which of the following statements is correct?

• A. Glucose is a ketose sugar.
• B. Glucose does not reduce Tollens' reagent.
• C. Glucose is oxidized to gluconic acid by \(Br_2(aq)\).
• D. Glucose gives negative Fehling test.

Hint:

Bromine water oxidizes aldehydes but does not oxidize ketones under ordinary conditions.

Answer 1

The Correct Option is C

Concept: Glucose is an aldohexose and contains an aldehyde functional group in its open-chain structure.

Step 1: Nature of glucose. Glucose contains six carbon atoms and one aldehyde group. Therefore, it is an aldose sugar, not a ketose sugar.

Step 2: Oxidation with bromine water. Bromine water is a mild oxidizing agent. It oxidizes aldehyde groups into carboxylic acids. Thus, glucose is oxidized to gluconic acid: \[ \mathrm{Glucose \xrightarrow{Br_2(aq)} Gluconic\ acid} \]

Step 3: Reducing nature of glucose. Because glucose contains an aldehyde group, it reduces: \[ \text{Tollens' reagent} \] and \[ \text{Fehling solution} \] Therefore, statements (2) and (4) are incorrect.

Step 4: Conclusion. Hence, option (3) is correct.