Optical isomerism is shown by the compound containing at least one chiral carbon atom (asymmetric). Optical isomers rotate the plane of polarised light. Generally, a chiral carbon atom is one that is attached to four different atoms or groups. Simple test of determining chirality of a three dimensional molecule is non-superimpossibility of its mirror images (Fig. 2). Polarized light is a light beam in which all the waves are vibrating in the same plane.