Question

If $n=2$ what are the values of quantum number $l$ and $m$?

Answer 1

$n=2$
The values of $l$ are from $0$ to $n-1$
$n-1=2=1$
so, $l=0,1$
$m$ values are from $-l$ to $+l$
so, $l=0,m=0$ and $l=1,m=-1,0,+1$