Answer
$\therefore \text{Number of oribtals in subshell 5f}=7 $
Work Step by Step
$\textbf{Note: }$Number of orbitals in a subshell ( $l$ ) is $2l+1$.
$5f$ corresponds to subshell $l=3$
$\therefore \text{Number of oribtals }=2\times 3+1=7 $