Question

D-glucose and D-galactose are C – 4 epimers.
A. True
B. False

Answer 1

Epimers are the isomers that differ from one another regarding the configuration (in spatial arrangement) particularly at a single carbon. Means epimers have differed in their arrangement particularly at one place.

Complete Solution :
- In the question it is asked whether G-glucose and D-galactose are C – 4 epimers or not.
- We should know the structures of the D-glucose and D-galactose to know whether they are C – 4 epimers or not.
- The structures of the D-glucose and D-galactose are as follows.

- By observing the above structures of the D-glucose and D-galactose, we can say that there are 6 carbons in D-glucose and D-galactose.
- The six carbon atoms are numbered with numbers.
- We can see there is a different arrangement of the hydrogen and hydroxyl group at carbon -4 in both the structures.
- Therefore D-glucose and D-galactose have the same arrangement at all carbons except at carbon-4.
- Then D-glucose and D-galactose are called as C- 4 epimers.
- Therefore, the given statement is True.
So, the correct answer is “Option A”.

Note: The two molecules D-glucose and D-galactose have different configurations at carbon-4 that is why they are called as C - 4 epimers. If the epimers have different arrangements at carbon – 1 then they are called as C -1 epimers. D- glucose and D- mannose are C- 2 epimers due to the difference in configuration at carbon – 2.