Question

which of the following statement/s is/are true?
a. glucose and galactose are c - 4 epimers because their structures differ only in the position of the hydroxyl group at carbon 2
b. glucose and mannose are c - 4 epimers.
c. galactose and mannose are isomers
d. a and b are true
e. none of the above

Explanation:

Step1: Define epimers

Epimers are diastereomers that differ in configuration at only one chiral carbon. Glucose and galactose are C - 4 epimers as they differ in the position of the hydroxyl group at carbon 4, not carbon 2, so A is false.

Step2: Analyze glucose - mannose relationship

Glucose and mannose are C - 2 epimers, not C - 4 epimers, so B is false.

Step3: Understand isomer concept

Isomers have the same molecular formula but different structures. Galactose and mannose have the same molecular formula ($C_6H_{12}O_6$) but different structures, so they are isomers and C is true. Since A and B are false, D is false. And since C is true, E is false.

Answer:

C. Galactose and mannose are isomers