How many optically active stereoisomers are possible for butane-2, 3-diol
1
2
3
4

Options

A. 1
B. 2
C. 3
D. 4

Answer

B

Explanation

(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`