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Structural isomers have obviously different constructions, but geometrical and optical isomers must be drawn or modelled in order to appreciate the difference in their three-dimensional arrangement. Geometrical isomers have a plane of symmetry and arise because of the restricted rotation of atoms around a bond; optical isomers are mirror images of each other. For instance, 1,1-dichloroethene (CH2
Blue stands for peace. The tassel is a symbol of the monarchy. Yellow represents mineral wealth. Red symbolizes battle. Effective date: 30 October 1967.
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