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JEE Main · 2022 · 26 Jul 2022 · Shift 1 · Biomolecules

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Which of the following is reducing sugar?
  1. (A)(see structure)
    ✓ Correct
  2. (B)(see structure)
  3. (C)(see structure)
  4. (D)(see structure)

Answer: (A)

Solution

A reducing sugar has a free anomeric –OH group (hemiacetal or hemiketal) that can open to form an aldehyde or ketone, which can reduce reagents like Fehling's or Benedict's solution. Option (A) shows a structure with a free anomeric –OH group, making it a reducing sugar. The other options have the anomeric carbon blocked (glycosidic linkage or acetal formation). Therefore, option (A) is correct.

JEE Main · 2022 · 26 Jul 2022 · Shift 1 · Single correct option

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