Give rules for writing resonance structures.

(N/A) $(i)$ The resonance structures must have the same positions of nuclei,i.e.,the atomic framework remains constant.
$(ii)$ The resonance structures must have the same number of unpaired electrons.
$(iii)$ Among the resonance structures,the one which has a greater number of covalent bonds,all atoms with a complete octet of electrons,less separation of opposite charges,and more dispersal of charge is more stable than others.