Question

In which of the following cases, both the compounds are examples of reducing sugars?

• A. Glucose and Sucrose
• B. Fructose and Maltose
• C. Fructose and Sucrose
• D. Sucrose and Lactose

Answer 1

The correct option is B Fructose and Maltose

In reducing sugars, free aldehyde/ketone group is present.
All monosaccharides and disaccharides are reducing sugar except sucrose which is a non-reducing sugar.
In sucrose, there is a glycosidic linkage between $C1$ of glucose and $C2$ of fructose. $C1$ of glucose contains free aldehyde group and $C2$ of fructose contains a ketone group. Thus, both these groups are not available for oxidation after formation of $C1-C2$ glycosodic linkage.
Hence, (b) is correct.
Fructose, lactose and Maltose are also reducing sugars.