Question

Electrons in excited hydrogen atoms are in the
n = 3 energy level. How many different photon
frequencies could be emitted as the atoms return
to the ground state?
(1) 1 (3) 3
(2) 2 (4) 4

Answer 1

I can see three different transitions here:

3 --> 1

3 --> 2
followed by
2 --> 1 .

So we should expect to see three different 'colors'
being emitted from this excited mob.