Which of the following elements has a half-filled valence shell?

Krypton $(_{36}Kr)$ has the electronic configuration $[Ar] 4s^2 3d^{10} 4p^6$. The $37^{th}$ electron will go into which of the following subshells?

The maximum number of orbitals present in $n=4$ energy level of an atom and the maximum number of electrons with spin value $+\frac{1}{2}$ in the same orbitals are, respectively.

The energy of an electron of $2p_y$ orbital is

What is the maximum number of electrons that can be accommodated in an orbital with $l = 3$?

The number of electrons that can be accommodated in $d_{z^2}$ orbital is