The maximum number of electrons in a $P$ orbital with $n = 6$ and $m = 0$ is ......

If the value of $(n+\ell)$ is not greater than $3$,which of the following subshells is not possible $-$

The relation between $n_m$ (the number of permissible values of magnetic quantum number $m$) for a given value of azimuthal quantum number $l$ is:

The orbital angular momentum of an electron in an $s$ orbital is

Two electrons occupying the same orbital are distinguished by

$A$ 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?