JEE Challenger
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ChemMedMain 2026 • 5th Apr - Shift 2

Evaluation of Statements on Glucose Anomers and Chiral Carbons

Given below are two statements :

Statement I : are two anomers of D-(+)-glucose\text{D-(+)-glucose}.

Statement II : The open chain forms of D-glucose and D-fructose contain three similar chiral carbons at C3\text{C}_3, C4\text{C}_4 and C5\text{C}_5.

In the light of the above statements, choose the correct answer from the options given below :

Question Diagram 1

Options

A

Both Statement I and Statement II are true

Correct
B

Both Statement I and Statement II are false

C

Statement I is true but Statement II is false

D

Statement I is false but Statement II is true

Topics & Concepts

BiomoleculesCarbohydrates

Step-by-Step Solution

To determine the correctness of the two statements, let us analyze them individually:

Analysis of Statement I:

Anomers are a specific type of epimers that differ in stereochemical configuration exclusively at the hemiacetal or hemiketal carbon (the anomeric carbon, C1\text{C}_1 in aldoses).

  • In the first structure of D-(+)-glucose\text{D-(+)-glucose}, the hydroxyl (−OH-\text{OH}) group at C1\text{C}_1 points downwards (trans to the −CH2OH-\text{CH}_2\text{OH} group at C5\text{C}_5), representing α-D-(+)-glucopyranose\alpha\text{-D-(+)-glucopyranose}.
  • In the second structure, the hydroxyl (−OH-\text{OH}) group at C1\text{C}_1 points upwards (cis to the −CH2OH-\text{CH}_2\text{OH} group at C5\text{C}_5), representing β-D-(+)-glucopyranose\beta\text{-D-(+)-glucopyranose}.

Since these two forms differ only in configuration at C1\text{C}_1, they are indeed two anomers of D-(+)-glucose\text{D-(+)-glucose}. Therefore, Statement I is true.

Analysis of Statement II:

Let us compare the Fischer projections for the open-chain structures of D-glucose and D-fructose:

  1. D-glucose (an aldohexose): C1HO−C2H(OH)−C3H(OH)−C4H(OH)−C5H(OH)−C6H2OH\text{C}_1\text{HO} - \text{C}_2\text{H(OH)} - \text{C}_3\text{H(OH)} - \text{C}_4\text{H(OH)} - \text{C}_5\text{H(OH)} - \text{C}_6\text{H}_2\text{OH}

    • Spatial configuration at chiral carbons:
      • C3\text{C}_3: −OH-\text{OH} on the left
      • C4\text{C}_4: −OH-\text{OH} on the right
      • C5\text{C}_5: −OH-\text{OH} on the right

  2. D-fructose (a ketohexose): C1H2OH−C2(=O)−C3H(OH)−C4H(OH)−C5H(OH)−C6H2OH\text{C}_1\text{H}_2\text{OH} - \text{C}_2(=\text{O}) - \text{C}_3\text{H(OH)} - \text{C}_4\text{H(OH)} - \text{C}_5\text{H(OH)} - \text{C}_6\text{H}_2\text{OH}

    • Spatial configuration at chiral carbons:
      • C3\text{C}_3: −OH-\text{OH} on the left
      • C4\text{C}_4: −OH-\text{OH} on the right
      • C5\text{C}_5: −OH-\text{OH} on the right

Both D-glucose and D-fructose share identical spatial arrangements at the three chiral centers C3\text{C}_3, C4\text{C}_4, and C5\text{C}_5. Therefore, Statement II is true.

Conclusion:

Since both statements are correct, the correct answer is Both Statement I and Statement II are true.

Evaluation of Statements on Glucose Anomers and Chiral Carbons | Chemistry PYQ Solution - JEE Challenger