Question

Define carbohydrates. What are reducing and non-reducing sugars?

Answer 1

Carbohydrates: Carbohydrates are optically active polyhydroxy aldehydes or polyhydroxy ketones, or the compounds which on hydrolysis produce polyhydroxy aldehydes or polyhydroxy ketones.
Examples: Glucose, Sucrose, Fructose.
Reducing sugars: Carbohydrates whic reduce Fehling solution to red ppt. of $C{u}_{2}O$ or Tollen's reagent to shinning metallic silver are called reducing sugars. All monosaccharides and oligosaccharides except sucrose are reducing sugars.
Non-reducing sugars: Carbohydrates which do not reduce Fehling solution and Tollen's reagent are called non-reducing sugars. E.g. Sucrose.