Maximum number of electrons that can be accommodated in the subshell with azimuthal quantum number $l=4$ is

$A$ 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?

Which one is a wrong statement?

Which of the following statements is not correct for an electron that has the quantum numbers $n = 4$ and $m_l = 2$?

If the electronic configuration of a nitrogen atom were $1s^7$,its energy would be lower than that of the ground state configuration $1s^2\,2s^2\,2p^3$ due to being closer to the nucleus. However,the $1s^7$ configuration is not observed because it violates which of the following rules?

For a given value of quantum number $l$,the number of allowed values of $m$ is given by