Question

Assertion (A): Maltose is a reducing sugar.
Reason (R): Maltose is composed of two glucose units in which C-1 of one glucose unit is linked to C-4 of another glucose unit.

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is not the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Hint:

Reducing sugars have at least one free anomeric carbon. In maltose, the second glucose retains its free C-1, making it a reducing sugar.

Answer 1

The Correct Option is A

Maltose is a disaccharide formed from two \(\alpha\)-D-glucose units. The glycosidic bond is formed between the C-1 of one glucose and C-4 of the other. Importantly: - One of the glucose units retains a free hemiacetal (anomeric) carbon. - This allows maltose to act as a reducing sugar. Thus: - Assertion is correct — maltose is indeed a reducing sugar. - Reason is also correct — the linkage involves C-1 to C-4. - Since the glycosidic linkage does not involve both anomeric carbons (unlike in sucrose), the free anomeric carbon enables reducing behavior. \[ \boxed{\text{Both A and R are true and R is the correct explanation of A.}} \]