chapter 14 Biomolecules Class 12 Chemistry Textbook Solution

2. Give scientific reasons :

i. The disaccharide sucrose gives negative Tollens test while the disaccharide maltose gives positive Tollens test.


  1. Sucrose’s molecular structure features a glycosidic linkage connecting the C-1 carbon of α-glucose and the C-2 carbon of β-fructose.

  2. Since both the monosaccharide units contribute their potential aldehyde and ketone groups to form the glycosidic bond (specifically, an α, β-1,2-glycosidic bond), sucrose qualifies as a non-reducing sugar and yields a negative result in the Tollen’s test.

  3. In maltose, the glycosidic bond forms between the C-1 carbon of one glucose ring and the C-4 carbon of the other glucose molecule (an α-1,4-glycosidic linkage).

  4. Notably, the hemiacetal group at C-1 of the second glucose ring remains uninvolved in the glycosidic linkage. Consequently, maltose is classified as a reducing sugar and produces a positive outcome in the Tollen’s test.

chapter 14 Biomolecules Class 12 Chemistry Textbook Solution

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