Expected products of hydrolysis of Lactose are:

The correct answer is Option (2) → Glucose and Galactose

Lactose (milk sugar) is a disaccharide composed of β-D-galactose and β-D-glucose, joined by a glycosidic linkage between C1 of galactose and C4 of glucose. Hydrolysis breaks this linkage and gives the two monosaccharides:

    \( \displaystyle \underset{\text{lactose}}{\ce{C12H22O11}} + \ce{H2O} \xrightarrow{\ce{H+}\text{ or lactase}} \underset{\text{galactose}}{\ce{C6H12O6}} + \underset{\text{glucose}}{\ce{C6H12O6}} \)

The products of hydrolysis of the three common disaccharides:

• Sucrose → α-D-glucose + β-D-fructose

• Maltose → two α-D-glucose

• Lactose → β-D-galactose + β-D-glucose

Why the other options are incorrect

• Option (1) Glucose and Fructose — Incorrect. These are the products of hydrolysis of sucrose (invert sugar).

• Option (3) Amylose and Amylopectin — Incorrect. These are the two components of starch, a polysaccharide; they are not formed from a disaccharide.

• Option (4) Ribose and Glucose — Incorrect. Ribose is the pentose sugar of RNA; it is not a unit of lactose.

NCERT (2026-27 edition):
Lactose

Note: The same/similar question has been asked in different years by NTA as per the details given below: