How many subshells are there in the shell with n = 3?

Nswer:
3 subshells.
Explanation:
I have written a similar answer to this question, I will copy it here I hope it helps:
Shell is the energy level of an atom (
n
=
1
,
2
,
3
,
e
t
c
.
). Inside every shell there is one or more subshells (
s
,
p
,
d
,
f
,
e
t
c
.
). Inside every subshell there is one or more orbitals .
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The best way to explain this is using the quantum numbers:
enter image source here
where,
n
: principal quantum number
l
: Angular momentum quantum number
The
s
subshell contains 1 orbital.
The
p
subshell contains 3 orbitals.
The
d
subshell contains 5 orbitals.
The
f
subshell contains 7 orbitals.

It shows that the experiment is designed properly.