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JEE Main · 2019 · 08 Apr 2019 · Shift 2 · Biomolecules

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Fructose and glucose can be distinguished by:
  1. (A)Benedict's test
  2. (B)Fehling's test
  3. (C)Barfoed's test
  4. (D)Seliwanoff's test✓ Correct

Answer: (D)

Solution

Both sugars are reducing, so tests like Benedict's and Fehling's respond to each and cannot separate them, and Barfoed's only tells monosaccharides from disaccharides. The distinguishing test is Seliwanoff's, which turns on the ketose versus aldose difference: fructose, a ketose, gives the red colour quickly, whereas glucose, an aldose, reacts only slowly. So Seliwanoff's test is the one that tells fructose from glucose.

JEE Main · 2019 · 08 Apr 2019 · Shift 2 · Single correct option

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