The set of quantum numbers not applicable for an electron in an atom is

The number of orbitals in $2p$ sub-shell is

Which of the following represents the electronic configuration of an element with atomic number $17$?

$A$ hydrogen atom has only one electron,so mutual repulsion between electrons is absent. However,in multielectron atoms,mutual repulsion between the electrons is significant. How does this affect the energy of an electron in the orbitals of the same principal quantum number in multielectron atoms?

The orbital with $4$ radial and $1$ angular nodes is

For how many electrons in an atom is $n = 3, m_l = 1$ possible?