Which pair of elements with the given atomic numbers is expected to have similar properties?

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.

In the following,the element with the highest electropositivity is

Which will show maximum non-metallic character?

Which of the following oxides is the most acidic?

Which block elements in the modern periodic table are the most electropositive?