Identify the orbital having the lowest energy from the following.

The number of angular nodes and radial nodes in $3s$ orbital are

The orbital angular momentum of a $p-$ electron is given as

The set of quantum numbers $n = 3$,$l = 0$,$m = 0$,$s = -1/2$ belongs to the element

$(i)$ 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?
$(a)$ $[He] 2s^{1}$
$(b)$ $[Ne] 3s^{2} 3p^{3}$
$(c)$ $[Ar] 4s^{2} 3d^{1}$

If $n$ and $l$ are principal and azimuthal quantum numbers respectively,then the expression for calculating the total number of electrons in any energy level is: