Question

Dextrororatory `alpha-`pinene has a specific rotation `[alpha]_(D)^(20) =+51.3^(@)`. A sample of `alpha-`pinene containing both the enantiomers was found to have a specific rotation value `[alpha]_(D)^(20) =+30.8^(@)`. The percentages of the `(+)` and `(-)` enantiomers present in the sample are, respectively,
A. 70% and 30%
B. 80% and 20%
C. 20%and 80%
D. 60%and 40%

Answer 1

Correct Answer - b
Optical purity `=(30.8)/(51.3)`
`rArr d=60%`
`rArr"Racemic"=40%`