JEE Main Chemistry Question (2026) — Solution

Step-by-step solution

Statement (A) is correct because all monosaccharides contain a free aldehyde or ketonic group (or exist in equilibrium with it) and act as reducing sugars. Statement (B) is incorrect because the hydrolysis of oligosaccharides can yield either the same or different monosaccharide units. For example, sucrose is an oligosaccharide (disaccharide) that yields one molecule of glucose and one molecule of fructose upon hydrolysis, whereas maltose yields two molecules of glucose. Statement (C) is correct as polysaccharides like starch and cellulose are high molecular weight polymers containing more than ten monosaccharide units. Statement (D) is correct because in an aqueous solution, D-(+)-glucose exists in an equilibrium between its open-chain form and its cyclic hemiacetal forms ( and anomers), which explains its mutarotation and other properties. Answer: The monosaccharide units obtained from hydrolysis of oligosaccharides are always the same.