Question

Which of the following are diasteromers?

• A. (I) and (III)
• B. (II) and (IV)
• C. (I) and (II)
• D. None

Answer 1

The correct option is C

(I) and (II)

The Fischer projection of (I) and (II) is wrond because the funtional group is not at the top. On rotating (I) and (II) by ${180}^{\circ }$, they are represented as shown:

Now compare I, II, III and IV.

(I) and (III) $\Rightarrow$ Enantiomers
(II) and (IV) $\Rightarrow$ Identica or same
Therefore, the pairs of diastereomers are:
(I), (II); (I), (IV); and (II), (III).
But the answer given is (C), (I<II).