How many electrons in an atom can have quantum numbers n = 3 and ml = +1 — JEE Chemistry

For $n = 3$: $l$ can be 0, 1, 2.

$m_l = +1$ is possible for $l = 1$ (one orbital: $3p$) and $l = 2$ (one orbital: $3d$).

Each orbital holds 2 electrons ($m_s = +\frac{1}{2}$ and $-\frac{1}{2}$):

$$Total = 2 + 2 = 4 electrons$$