Explain the method of writing `E-Z` configurations for geometrical isomers taking `CHCl - CFBr` as your example.

Explanation

E-Z configurations for geometrical isomers : The following procedure is followed in specifying the configurations of compounds:
i) Arrange the atoms / groups attached to each doubly bonded carbon in the order of their atomic numbers:
ii) Choose the atom/group higher priority on each doubly bonded carbon. If the atoms/groups of higher priority on each carbon are on the same side of the molecule, the letter "Z" is used to denote the configuration of such isomer. When the atoms/groups of higher priority on each carbon are on the opposite sides of the molecule, the letter .E. is prefixed before the name to indicate configuration.
Example : CHCl = CFBr
Among H cna `Cl _(17), Cl ` gets more priority then `""_(1) H.`
Among F and `Br, _(17)Cl` gets more priority than `""_(9) F.`