How many electrons can be accommodated in a sub-shell for which $n = 3, l = 1$?

What is the total number of orbitals associated with the principal quantum number $n = 3$?

Identify the correct statements among the following:
$i. E_{2s}(H) > E_{2s}(Li) < E_{2s}(Na) > E_{2s}(K)$
$ii.$ The maximum number of electrons in the shell with principal quantum number $n$ is equal to $2n^2$.
$iii.$ Extra stability of half-filled subshell is due to smaller exchange energy.
$iv.$ Only two electrons,irrespective of their spin,may exist in the same orbital.

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

What is a nodal surface?

How many electrons can fit in the orbital for which $n = 3$ and $l = 1$?