Statement I: Maltose is a reducing sugar which gives two moles of D-glucose on hydrolysis.
Statement II: Maltose has a 1,4-\(\beta\)-glycosidic linkage.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Statement I is correct but Statement II is false
Maltose is a disaccharide made of two α-D-glucose units joined by a glycosidic linkage between C1 of one unit and C4 of the other.
Statement I: Maltose is a reducing sugar which gives two moles of D-glucose on hydrolysis. — True. Both units are glucose, so hydrolysis gives two molecules of glucose only. The C1 of the second glucose unit is not used in the linkage, so a free aldehyde group can form there in solution and maltose is a reducing sugar.
Statement II: Maltose has a 1,4-\(\beta\)-glycosidic linkage. — False. The linkage starts from C1 of an α-D-glucose unit, so it is an α-1,4 glycosidic linkage. A β-1,4 linkage between glucose units is found in cellulose.
NCERT (2026-27 edition):
10.1.3 Disaccharides – “(ii) Maltose: Another disaccharide, maltose is composed of two α-D-glucose units in which C1 of one glucose (I) is linked to C4 of another glucose unit (II). The free aldehyde group can be produced at C1 of second glucose in solution and it shows reducing properties so it is a reducing sugar.”
10.1.1 Classification of Carbohydrates – “… For example, one molecule of sucrose on hydrolysis gives one molecule of glucose and one molecule of fructose whereas maltose gives two molecules of only glucose.”