Question

Those stereoisomers which are differing in its configuration at only one chiral carbon atom are called as 'epimers'.
How many of the following are epimers of $D-(+)-$glucose?

Answer 1

Answer: 2

When the structure of $D$-glucose is compared with the structure (iii), the configuration of $2$ carbon atoms ($C-2$ and $C-4$) are different.
When the structure of $D$-glucose is compared with the structure (iv), the configuration of $2$ carbon atoms ($C-2$ and $C-3$) are different.