Which of the given elements $A$,$B$,$C$,$D$ and $E$ with atomic numbers $2$,$3$,$7$,$10$ and $30$ respectively belong to the same period?

State whether the following statements are true or false: In the Modern Periodic Table,a zig-zag line separates metals from non-metals. The borderline elements—boron,silicon,germanium,arsenic,antimony,tellurium,and polonium—are intermediate in properties and are called metalloids or semimetals.

The electronic configuration of an element $X$ is $2, 8, 8, 2$. To which $(a)$ period and $(b)$ group of the modern periodic table does $X$ belong? State its valency. Justify your answer in each case.

$(a)$ Identify the element that has two completely filled shells and the number of valence electrons in each are as: $(i)$ $1$,$(ii)$ $2$,$(iii)$ $7$,$(iv)$ $8$. $(b)$ Analyse which amongst them is inert.

$Lithium$,$sodium$,and $potassium$ are all metals that react with water to liberate hydrogen gas. Is there any similarity in the atoms of these elements?

How does the electronic configuration of an atom relate to its position in the Modern Periodic Table?