Which of the following is $Not$ predominantly acidic or amphoteric oxide?

The correct order of increasing metallic character of $Na$, $Be$, $P$, $Mg$ and $Si$ is:

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.

The diagonal relationship between $Be$ and $Al$ is due to:

Which of the following orders is correct?

Among the following,the least and most metallic elements will be respectively:
$(I) [He] 2s^1$
$(II) [Kr] 5s^2 4d^{10} 5p^5$
$(III) [Xe] 6s^1$
$(IV) [He] 2s^2 2p^5$