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

How does the chemical reactivity change as we move from left to right across a period in the periodic table?

In $s-$block,on moving down the group,the reactivity of metals with water and air increases. Which of the following factors has no significance for this trend of reactivity?

Which properties in a period indicate the chemical reactivity of elements?

The element with $ns^2np^2$ valence shell configuration belongs to which group?

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 $(F)$?