Assuming that elements are formed to complete the $7^{th}$ period,what would be the atomic number of the alkaline earth metal of the $8^{th}$ period?

Which among the following electronic configurations belong to main group elements?
$A. [Ne] 3s^1$
$B. [Ar] 3d^3 4s^2$
$C. [Kr] 4d^{10} 5s^2 5p^5$
$D. [Ar] 3d^{10} 4s^1$
$E. [Rn] 5f^0 6d^2 7s^2$
Choose the correct answer from the options given below:

To which group of the periodic table does an element having electronic configuration $[Ar] 3d^5 4s^2$ belong?

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

What is the temporary symbol of an element with an atomic number of $116$?

What will be the $IUPAC$ symbol and name for the element with atomic number $123$?