Consider the following.

(I) The order of first ionisation enthalpy of first three elements of 3rd period is $\mathrm{Mg}>\mathrm{Al}>\mathrm{Na}$.

(II) The element with electronegativity of 3.5 is chlorine.

(III) The order of sizes of ions $\mathrm{Mg}^{2+}, \mathrm{Na}^{+}, \mathrm{F}^{-}$and $\mathrm{O}^{2-}$ is $\mathrm{Mg}^{2+}<\mathrm{Na}^{+}<\mathrm{F}^{-}<\mathrm{O}^{2-}$.

(IV) The IUPAC name of the element with atomic number 106 is bohrium.

The correct statements are

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 $\mathrm{Cl}>\mathrm{Br}>\mathrm{I}$.

Which of the following sequence is correct for decreasing order of ionic radius?

The successive ionisation energies (starting from the 1 st ) of an element are $801,2430,3660,25,000$ and $32,800 \mathrm{~kJ} \mathrm{~mol}^{-1}$, respectively. The element is