Chemistry - STEREO ISOMERISM Question with Solution | TestHub

trans-1,2-Dichloroethene has only one plane of symmetry: σxy, the molecular plane containing all the atoms. The perpendicular plane σyz is not a symmetry plane here, because reflecting across it would interchange a Cl atom with an H atom on the same carbon. It also has a centre of symmetry at the midpoint of the C=C bond. cis-1,2-Dichloroethene has both planes; the trans isomer has only the molecular plane.