The possible values of $l$ are $0, 1, 2, 3$.
Work Step by Step
*NOTES TO REMEMBER: - The angular momentum quantum number $l$ can have values from $0$ to $(n-1)$ for each value of $n$. - The magnetic quantum number $m_l$ can have integral values from $-l$ to $l$, including $0$. Therefore, for $n=4$, the possible values of $l$ are $0, 1, 2, 3$.