Question

How many optically active stereiosomers are possible of butane `2,3` diol?
A. 1
B. 2
C. 3
D. 4

Answer 1

Correct Answer - B
(Number of aymmetric C atoms =2)
Terminal group are same.
Number of `O.A` isomers `=2^(n-1)=2^(2-1)=2^(1)=2`
Number of meso forms `=2^((n-2)//2)=2^(0)=1`