Answer
(a) $L = 1.41~\hbar$
(b) $L = 3.46 ~\hbar$
Work Step by Step
(a) In the $4p$ state, $l = 1$
We can find the angular momentum:
$L = \sqrt{l~(l+1)}~\hbar$
$L = \sqrt{(1)~(1+1)}~\hbar$
$L = 1.41~\hbar$
(b) In the $5f$ state, $l = 3$
We can find the angular momentum:
$L = \sqrt{l~(l+1)}~\hbar$
$L = \sqrt{(3)~(3+1)}~\hbar$
$L = 3.46 ~\hbar$
