Out of the following reducing sugars are?
(A) Sucrose
(B) Lactose
(C) Maltose
(D) Galactose
Answer & explanation
Correct answer: option 3
The correct answer is option 3. B, C, D.
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A. Sucrose: Non-reducing sugar. The reducing groups (anomeric carbons) of both glucose and fructose are involved in the glycosidic linkage, leaving no free hemiacetal group to reduce Tollen's or Fehling's reagents.
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B. Lactose: Reducing disaccharide. It retains a free anomeric carbon on its glucose unit.
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C. Maltose: Reducing disaccharide. It retains a free anomeric carbon on one of its glucose units.
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D. Galactose: Reducing monosaccharide. All monosaccharides (both aldoses and ketoses) possess free reducing groups and act as reducing agents.
Therefore, Lactose, Maltose, and Galactose are all reducing sugars.
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