All the elements in a group in the periodic table have the same

$Be$ and $Al$ resemble in:

The electronic configuration of three elements $A, B$ and $C$ are given below. The molecular formula of the compound formed from $B$ and $C$ will be
$A : 1s^2, 2s^2, 2p^6$
$B : 1s^2, 2s^2, 2p^6, 3s^2, 3p^3$
$C : 1s^2, 2s^2, 2p^6, 3s^2, 3p^5$

In the following,the element with the highest electropositivity is

The correct order of acidic strength is:

Identify the correct order of basicity for the following oxides: $Na_2O, MgO, CuO, SiO_2$.