Question

Total number of plane of symmetry in all isomers of dichlorobenzene is:

Answer 1

In all these isomers, the plane of molecule is the plane of symmetry. This accounts for three planes. In ortho isomer, the plane perpendicular to the plane of molecule which is present midway between the two chlorine atoms is the plane of symmetry. Same is true for meta isomer. Thus in total 5 planes of symmetry are accounted for. In the para isomer, two planes perpendicular to the plane of molecule, on passing through two chlorine atoms and other
perpendicular to it are the planes of symmetry. Thus, in total, there are seven planes of symmetry in all the isomers of dichloro benzene.