Consider the elements Mg, Al, S, P and Si, the correct increasing order of their first ionization enthalpy is :

The correct order of the ionic radii of
O^2–, N^3–, F^– , Mg²⁺, Na⁺ and Al³⁺ is :

The ionic radii of O^2–, F^–, Na⁺ and Mg²⁺ are in the order :

Among the statements (I – IV), the correct ones are:
(I) Be has smaller atomic radius compared to Mg.
(II) Be has higher ionization enthalpy than Al.
(III) Charge/radius ratio of Be is greater than that of Al.
(IV) Both Be and Al form mainly covalent compounds.