What are the major differences between metals and non-metals?

Which of the following pairs has elements containing the same number of electrons in the outermost orbit?

The correct order of acid strength is

The correct order of the non-metallic character among the elements $B, C, N, F$ and $Si$ is

Match the following:

Oxide	Nature
$a$. $CO$	$i$. Basic
$b$. $BaO$	$ii$. Neutral
$c$. $Al_2O_3$	$iii$. Acidic
$d$. $Cl_2O_7$	$iv$. Amphoteric

Which of the following is the correct option?

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.