Which of the following rules states that an orbital can hold a maximum of two electrons?

An atom with atomic number $15$ contains:

The total value of magnetic quantum number for $n = 4$ is:

The number of orbitals with $n = 5, m_{l} = +2$ is $......$ . (Round off to the Nearest Integer)

Krypton $(_{36}Kr)$ has the electronic configuration $(_{18}Ar) \ 4s^2, 3d^{10}, 4p^6$. The $37^{th}$ electron will go into which one of the following sub-levels?

Although no currently known element contains electrons in $g$ orbitals in the ground state,it is possible that such an element will be found or that electrons in excited states of known elements could be in $g$ orbitals. For $g$ orbitals,$l = 4$. What is the lowest value of $n$ for which $g$ orbitals could exist? What are the possible values of $m_l$? How many electrons could a set of $g$ orbitals hold?