The angular momentum of a $p$-orbital electron is given by:

Which of the following orbitals will have $2$ nodal planes and $4$ total nodes?

The correct set of four quantum numbers for the valence electron of rubidium atom $(Z=37)$ is:

Which of the following statements are correct?
$(a)$ When an electron in an atom moves from $n=4$ to $n=2$,it gains energy.
$(b)$ An electron in a $3p$ orbital would have less energy than an electron in a $2p$ orbital.
$(c)$ $A$ $3s$ subshell has a maximum of $2$ electrons.
$(d)$ $A$ $3^{rd}$ orbit may contain a maximum of $10$ electrons.

What are the four quantum numbers for the valence electron of sodium $(Z = 11)$?

For both $2p$ and $3s$ orbitals,the value of $(n + l)$ is equal to $3$. Which of these has lower energy and why?