The principal quantum number of an atom represents:

The maximum number of electrons that can be filled in the shell with the principal quantum number $n=3$ is

If $n = 3$,which of the following values of $l$ is correct?

Which orbital is dumb-bell shaped?

The energy of an electron of $2p_y$ orbital is

Five valence electrons of $P^{15}$ are labelled as $\boxed{AB}_{3s} \,\boxed{X|Y|Z}_{3p}$. If the spin quantum numbers of $B$ and $Z$ are $+\frac{1}{2}$,the group of electrons with three of the quantum numbers $(n, l, m)$ the same are: