Which of the following is non-reducing sugar ?

Options

A. Glucose
B. Sucrose
C. Maltose
D. Lactose

Answer

To determine which of the following sugars is a non-reducing sugar, we need to understand the concept of reducing and non-reducing sugars.

### Step 1: Understanding Reducing and Non-Reducing Sugars
- **Reducing sugars** are sugars that can be oxidized by mild oxidizing agents (like Tollen's reagent or Fehling's reagent). They typically have a free aldehyde or ketone group.
- **Non-reducing sugars** do not have a free aldehyde or ketone group and cannot be oxidized by these agents.

### Step 2: Identify the Sugars
The sugars we need to evaluate are:
1. Glucose
2. Sucrose
3. Maltose
4. Lactose

### Step 3: Analyze Each Sugar
- **Glucose**: This is a reducing sugar because it has a free aldehyde group.
- **Maltose**: This is also a reducing sugar as it has a free anomeric carbon with a hydroxyl group.
- **Lactose**: This is a reducing sugar because it contains a free anomeric carbon.
- **Sucrose**: This is a non-reducing sugar because both of its anomeric carbons (from glucose and fructose) are involved in the glycosidic bond, meaning there are no free hydroxyl groups available for oxidation.

### Step 4: Conclusion
Based on the analysis, the non-reducing sugar among the options provided is **sucrose**.

### Final Answer
The non-reducing sugar is **sucrose**.

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