In the modern periodic table,elements are arranged in

The element with atomic number $6$ is placed in:

How would you justify the presence of $18$ elements in the $5^{\text{th}}$ period of the Periodic Table?

Match the elements in List-$I$ with their symbols in List-$II$.

List-$I$	List-$II$
$(1)$ $Unnilbium$	$(A)$ $Db$
$(2)$ $Unnilennium$	$(B)$ $Lr$
$(3)$ $Unnilpentium$	$(C)$ $Mt$
$(4)$ $Unniltrium$	$(D)$ $Bh$
	$(E)$ $No$
	$(F)$ $Rg$

Determine the position of the element in the periodic table for the following outer electronic configurations:
$(i)$ $ns^2 np^4$ where $n = 3$
$(ii)$ $(n-1)d^2 ns^2$ where $n = 4$
$(iii)$ $(n-2)f^7 (n-1)d^1 ns^2$ where $n = 6$

The number of elements in the $5^{th}$ period of the periodic table are