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JEE Main · 2026 · 28 Jan 2026 · Shift 2 · Biomolecules

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Structures of four disaccharides are given below. Among the given disaccharides, the non-reducing sugar is :
  1. (A)(see structure)
    ✓ Correct
  2. (B)(see structure)
  3. (C)(see structure)
  4. (D)(see structure)

Answer: (A)

Solution

A non-reducing sugar has both anomeric carbons locked in the glycosidic bond, leaving no free hemiacetal. The disaccharide in which a glucopyranose unit is joined through its anomeric carbon to the anomeric carbon of a fructofuranose unit is sucrose; with both reducing centres engaged it cannot open to an aldehyde or ketone and gives no reaction with Tollens' or Fehling's reagents. The other three structures each retain a free anomeric hydroxyl and are reducing. The non-reducing sugar is sucrose.

JEE Main · 2026 · 28 Jan 2026 · Shift 2 · Single correct option

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