Question

Sucrose is NOT a reducing sugar since

• A. it is chemically stable
• B. it contains no free aldehyde or keto group adjacent to , $>CHOH$ group
• C. it is built up of a fructose unit
• D. it is optically active

Answer 1

Answer: (B)

it contains no free aldehyde or keto group adjacent to , $>CHOH$ group

Answer 2

Carbohydrates which can reduce Tollen's reagent or Fehling solution are called reducing sugars. All the monosaccharides and the disaccharides (except sucrose) are reducing agent.

Sucrose does not have free aldehyde or keto group adjacent to $> CHOH$ group, therefore it fails towards Tollen's reagent and Fehling solution.