Chemistry - STEREO ISOMERISM Question with Solution | TestHub

Ans. (B) 2.

Sol. The molecule has four stereocentres (the two ring carbons at 1,3 and the two side-chain methine carbons), with a symmetry exchanging the two halves. Writing the configuration of one half as (a,b), meso forms require the mirror image to be superimposable, i.e. the second half must be the mirror of the first; the two free choices give (R,R,S,S) and (R,S,S,R) after accounting for the molecular symmetry. Meso-isomers = 2.