CGPET 2013 Solved Paper

Isomerism which occurs due to different relative arrangements of ligands around central metal atom is known as geometrical isomerism.
Complexes of formula MABCD may exist in three isomeric forms.
‌ e.g., ‌[Pt(NH3)(Br)(Cl)(Py)]square planar complexes do not show optical isomerison since they are not optically active as they have all the ligands and metal atoms in one plane, that's why there is a plane of symmetry.