An ion with a charge of $-2$ has the electronic configuration $1s^2, 2s^2, 2p^6$. Identify the ion.

Five valence electrons of $P^{15}$ are labelled as $\boxed{AB}_{3s} \,\boxed{X|Y|Z}_{3p}$. If the spin quantum numbers of $B$ and $Z$ are $+\frac{1}{2}$,the group of electrons with three of the quantum numbers $(n, l, m)$ the same are:

Which of the following elements has the least number of electrons in its $M$ shell?

The energy of atomic orbitals in a given shell follows the order:

Which of the following is the correct electronic configuration of $Cr$?

Which of the following pairs of $d-$ orbitals will have electron density along the axes?