The element with the electronic configuration $1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10} 4s^1$ is

$(i)$ Write the electronic configurations of the following ions:
$(a)$ $H^{-}$
$(b)$ $Na^{+}$
$(c)$ $O^{2-}$
$(d)$ $F^{-}$
$(ii)$ What are the atomic numbers of elements whose outermost electrons are represented by
$(a)$ $3s^{1}$
$(b)$ $2p^{3}$ and
$(c)$ $3p^{5}$?
$(iii)$ Which atoms are indicated by the following configurations?
$(a)$ $[He] 2s^{1}$
$(b)$ $[Ne] 3s^{2} 3p^{3}$
$(c)$ $[Ar] 4s^{2} 3d^{1}$

The number of electrons present in all the completely filled subshells having $n=4$ and $s=+\frac{1}{2}$ is . . . . . . . (Where $n=$ principal quantum number and $s=$ spin quantum number)

Which electron is associated with the least energy?

The atom of the element having atomic number $14$ should have:

The values of $n$ and $l$ for orbital $A$ are $3$ and $2$ respectively. The values of $n$ and $l$ for orbital $B$ are $5$ and $0$ respectively. Compare their energies.