Which of the following is an oligosaccharide?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Maltose
Oligosaccharides give two to ten monosaccharide units on hydrolysis, and the most common of them are the disaccharides. Maltose is a disaccharide: on hydrolysis it gives two molecules of α-D-glucose.
\( \ce{C12H22O11 + H2O -> 2C6H12O6} \)
Why the other options are incorrect
Option (1) Starch — Incorrect. A polysaccharide, the storage carbohydrate of plants, which gives a large number of glucose units on hydrolysis.
Option (2) Glucose — Incorrect. A monosaccharide; it cannot be hydrolysed into simpler sugars.
Option (3) Ribose — Incorrect. A monosaccharide (an aldopentose), the sugar unit of RNA; it cannot be hydrolysed further.
NCERT (2026-27 edition):
Classification of Carbohydrates – …
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.”
Note: The same/similar question has been asked in different years by NTA as per the details given below:
| 2026 | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| – | – | – | – | 23-08 S1 10-08 S1 |