Question

How many optically active stereoisomers are possible for butane-2, 3 diol
A. 1
B. 2
C. 3
D. 4

Answer 1

Correct Answer - B
`{:(CH_(3)-overset(**)(C)H-overset(**)(C)H-CH_(3)),(" |"" |"),(" "OH" "OH):}`
In it two asymmetric C-atoms and a plane of symmetry are present. So optically active isomers `= 2^(n+1) = 2^(2-1) = 2`
(n = No. of asymmetric carbon atoms.)