The electronic configurations of four elements are given in brackets:
$L(1s^2, 2s^2\ 2p^1);$ $M(1s^2, 2s^2\ 2p^5)$
$Q(1s^2, 2s^2\ 2p^6, 3s^1);$ $R(1s^2, 2s^2\ 2p^2)$
The element that would most readily form a diatomic molecule is:

Values of the four quantum numbers for the last electron in the atom are $n = 4, l = 1, m = +1$ and $s = -1/2$. Atomic number of the atom will be

Which of the following $p, d, f$ orbitals are not possible? Why?

Which of the following is not a permissible arrangement of electrons in an atom?

The atomic number of the element having the maximum number of unpaired electrons (in the ground state) 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?
$(a)$ $[He] 2s^{1}$
$(b)$ $[Ne] 3s^{2} 3p^{3}$
$(c)$ $[Ar] 4s^{2} 3d^{1}$