question_answer

The number of optically active isomers of tartaric acid are:

A)  1                

B)  3

C)  4               

D)  2

Correct Answer: D

Solution :

Key Idea: Optical isomerism is shown by compounds in which at least one asymmetric carbon atom and it should not have plane of symmetry. Tartaric acid has 2 asymmetric carbon atoms. Total no. of optical isomers \[={{(2)}^{n}}\] (where n = no. of asymmetric carbon atom).                 \[={{(2)}^{2}}=4\] Out of these 4 optical isomers two are meso structures which are optically in active. \[\therefore \] Only 2 structures d and \[l\] tartaric acid are optically active.