Answer: Chiral and not superimposable on its mirror image.
- A Chiral and not superimposable on its mirror image
- B Contain an even number of chiral centres in routine practice
- C Have a meso form overall in most cases under typical conditions
- D Contain mainly carbon and hydrogen according to standard textbooks
Correct answer: A. Chiral and not superimposable on its mirror image
Explanation: Optical activity requires a molecule to be chiral (non-superimposable on its mirror image), which is indicated by the presence of a stereocentre without an internal plane or axis of symmetry.
SN2 proceeds in a single step with backside attack and inversion of configuration, while SN1 forms a planar carbocation intermediate first, leading to racemisation.
Concept context
Study carbon-halogen compounds: how they are made, how they react via SN1/SN2 and elimination, their stereochemistry, and their environmental impact.