Question

Which of the following pair of monosaccharides contains epimers of each other?

• A. D-Mannose and D-Glucose
• B. D-Gulose and D-Glucose
• C. D-Arabinose and L-Arabinose
• D. D-Glucose and D-Fructose

Hint:

Epimers differ at a single chiral center (not the anomeric carbon). Remember: D-Mannose and D-Glucose differ at C-2 — making them classic epimers.

Answer 1

The Correct Option is A

Step 1: Define epimers.
Epimers are isomers of monosaccharides that differ in configuration at only one specific chiral carbon atom, other than the anomeric carbon. Step 2: Analyze the options.
D-Mannose and D-Glucose differ at C-2 — they are C-2 epimers.
D-Gulose and D-Glucose differ at more than one chiral center.
D-Arabinose and L-Arabinose are enantiomers, not epimers.
D-Glucose and D-Fructose are structural isomers (aldose vs ketose), not epimers.
Conclusion:
Only D-Mannose and D-Glucose qualify as epimers, differing only at the second carbon.