ΓΌ  Oxoacids of Halogens: The term oxoacid now refers to a compound which contains oxygen, at least one other element, and at least one hydrogen bound to oxygen.
·    Fluorine forms only one oxoacid HOF (Fluoric (I) acid or hypofluorous acid) dueto high electronegativity.
·     The other halogens form several oxoacids like Hypohalous acid (HOX), halous acid (HOXO), halic acid (HOXO2) and perhalic acid (HOXO3). They are stable only in aqueous solutions or in the form of their salts.
·     Chlorine forms 4 types of oxoacids – hypochlorous acid (HOCl), Chlorous acid (HOClO or HClO2), Choric acid (HOClO2 or HClO3) and perchloric acid (HOClO3 or HClO4). The structures of them are:



·       Acid strength: HOCl < HClO2 < HClO3 < HClO4
            Reason: HClO4 → H+ + ClO4-
             most stable
·       Acid strength: HOF > HOCl > HOBr > HOI
           This is because Fluorine is most electronegative.