Which of the following statements is/are false?
I. The resonance structures have different positions of nuclei.
II. Resonance structures have the same number of unpaired electrons.
III. Among the resonance structures, the one which has more number of covalent bonds, all the atoms with octet of electrons and more dispersal of charge is more stable than others.
     Choose the correct option.

The following rules are applied while writing resonance structures:
The resonance structures have 

(i) the same positions of nuclei

(ii) the same number of unpaired electrons. Among the resonance structures, the one which has more number of covalent bonds, all the atoms with octet of electrons (except hydrogen which has a duplet), less separation of opposite charges , ( a negative charge, if it is on more electronegative atom, a positive charge, if it is on more electropositive atom) and more dispersal of charge, is more stable than the other.