What are reducing sugars ?

Explanation

Carbohydrates which reduces Fehling's solution to red precipitate of `Cu_(2)O` or Tollen's reagent to metallic Ag are called reducing sugars. All monosaccharides (both aldoses and ketoses) and disaccharides excepts sucrose are reducing sugars. Thus, `D - (+) -` glucose, `D-(-)-` fructose, `D - (+) -` maltose and `D - (+) -` lactose are reducing sugars.