Question

Compound A gives D-Galactose and D-Glucose on hydrolysis. The compound A is :

• A. Maltose
• B. Lactose
• C. Sucrose
• D. Amylose

Hint:

Memorize the composition of common disaccharides: Sucrose = Glucose + Fructose; Lactose = Galactose + Glucose; Maltose = Glucose + Glucose.

Answer 1

The Correct Option is B

The question states that hydrolysis of compound A yields two different monosaccharides: D-Galactose and D-Glucose. This means compound A is a disaccharide composed of these two units.
Let's examine the hydrolysis products of the options:
(A) Maltose: On hydrolysis, maltose yields two molecules of D-Glucose.
(B) Lactose: On hydrolysis, lactose (also known as milk sugar) yields one molecule of D-Galactose and one molecule of D-Glucose. This matches the description in the question.
(C) Sucrose: On hydrolysis, sucrose yields one molecule of D-Glucose and one molecule of D-Fructose.
(D) Amylose: This is a polysaccharide, a polymer of D-Glucose. On complete hydrolysis, it yields many molecules of D-Glucose.
Therefore, the compound A is Lactose.