# Enantiomers and diastereomers [closed]

I don't understand why on the problem a. B and C are enantiomers, while on the problem b. B is identical to the last molecule.

• In the 1,3-disubstituted cyclohexanes, A can jump over the mirror and superimpose on its mirror image. It has a plane of symmetry. B and C cannot superimpose on one another. No symmetry plane in B or C. May 12 at 23:17

Ask yourself this: in problem $$a$$, are B and C superimposable on each other? You'll find that that is not the case. So those two are enantiomers. In problem $$b$$, B and its mirror image are perfectly superimposable on each other, hence identical. This also shows that in problem $$a$$, B is am optically active molecule, while in problem $$b$$ it is not.