The number of subshells associated with n = 4 and m = - 2 quantum...

For $n = 4$ possible values of $ℓ = 0, 1, 2, 3$ because values $ℓ$ lie between $0ton - 1$

We have to check values of $m$ which lie between $- ℓto + ℓ$.

$ℓ = 2 \text{ and } ℓ = 3$ can have $m = - 2$ So possible subshells are $2$.