Question

On hydrolysis, which of the following carbohydrates gives only glucose?

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

Hint:

Maltose gives only glucose on hydrolysis. Sucrose gives glucose and fructose; lactose gives glucose and galactose.

Answer 1

The Correct Option is D

Concept:
Disaccharides on hydrolysis give monosaccharide units. Different disaccharides give different monosaccharides. \[ \text{Sucrose} \rightarrow \text{Glucose}+\text{Fructose} \] \[ \text{Lactose} \rightarrow \text{Glucose}+\text{Galactose} \] \[ \text{Maltose} \rightarrow \text{Glucose}+\text{Glucose} \]

Step 1: Check sucrose.
Sucrose gives glucose and fructose on hydrolysis. \[ \text{Sucrose}+H_2O \rightarrow \text{Glucose}+\text{Fructose} \] So sucrose does not give only glucose.

Step 2: Check lactose.
Lactose gives glucose and galactose. \[ \text{Lactose}+H_2O \rightarrow \text{Glucose}+\text{Galactose} \] So lactose also does not give only glucose.

Step 3: Check maltose.
Maltose is made up of two glucose units. On hydrolysis: \[ \text{Maltose}+H_2O \rightarrow 2\text{Glucose} \] Therefore, maltose gives only glucose. Hence: \[ \boxed{\text{(D) Maltose}} \]