How many sub-shell are there in `N` shell ? How many orbitals are there in `d` sub-shell ?

Answer

For `N` shell principal quantum number, `n=4`
Number of sub-shells in an energy level`=n`
`:.` Number of sub-shells in `N` shell `=4`
(b) for `d` subshell `l=2`
Number of orbitals in a sub-shell `=2l+1`
Number of orbitals in a `d`-sub shell `=(2xx2)+1=5`