Which of the following sets of elements have the strongest tendency to form anions?

Which of the following is the most basic oxide?

The chemistry of lithium is very similar to that of magnesium even though they are placed in different groups. Why?

The chemical properties of $Li$ and $Mg$ are similar because:

The electronic configurations of four elements are:
$I.$ $[Kr]\, 5s^1$
$II.$ $[Rn]\, 5f^{14}\, 6d^1\, 7s^2$
$III.$ $[Ar]\, 3d^{10}\, 4s^2\, 4p^5$
$IV.$ $[Ar]\, 3d^6\, 4s^2$
Consider the following statements:
$(i)$ $I$ shows variable oxidation state
$(ii)$ $II$ is a $d$-block element
$(iii)$ The compound formed between $I$ and $III$ is covalent
$(iv)$ $IV$ shows single oxidation state
Which statement is True $(T)$ or False $(F)$?

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