Periodic Table And Periodicity

Identify the correct statements from the following.

(I) Au is soluble in aqua regia but not Pt .

(II) Among the oxoacids of chlorine highest oxidation state possible for chlorine is +7 .

(III) Among the hydrogen halides lowest boiling point is for HCl .

(IV) The order of stability of oxides of halogens is $\mathrm{Cl}>\mathrm{Br}>\mathrm{I}$.