Q. An optically active compound $A$, gave an $\lbrack\alpha\rbrack_{D}^{25} = 30{^\circ},$ while a mixture of $A$ and its enantiomer $B,$ gave $\lbrack\alpha\rbrack_{D}^{25} = + 15{^\circ}.$ The ratio of $A$ and $B$ in the mixture is
A) 1 to 3
B) 3 to 1
C) 1 to 2
D) 2 to 1
Explanation
(b)
$\frac{15}{30} \times 100 = 50$
Thus, the mixture is 50% optically pure. Hence, the amount of
$A = 50 + 25 = 75$
$B = 0 + 25 = 25$
$A\ :B = 3\ :1$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.