Assertion (A): Molecules that are not super-impossible on their mirror images are chiral.
Reason ( R): All chiral molecules have chiral centres
 

Molecules that are not superimposable on their mirror images are chiral is correct statement.

All chiral molecules have chiral centers is wrong statement.

For example, if the two methyl groups were cis, then the molecule would still have two chiral centers but not be chiral and would be a meso compound.