I) ‘X’ is aromatic compound

II) ‘X’ is benzene hexachloride

III) ‘X’ is used as insecticide

IV) ‘X’ is hexachloro benzene

If excess of electrophilic reagent is used, further substitution reaction may take place in which other hydrogen atoms of benzene ring may also be successively replaced by the electrophile. For example, benzene on treatment with excess of chlorine in the presence of anhydrous AlCl₃ can be chlorinated to hexachlorobenzene (C₆Cl₆)