Answer:
a) the three longest wavelengths = 4.8m, 2.4m, 1.6m
b) what is the frequency of the third-longest wavelength = 75Hz
Explanation:
The steps and appropriate formula and substitution is as shown in the attached file.
the action and reaction do not lead equilibrium if action and reaction force react on different objects
Answer:
E=-1.51 eV.

Explanation:
The nth level energy of a hydrogen atom is defined by the formula,

Given in the question, the hydrogen atom is in the 3p state.
Then energy of n=3 state is,

Therefore, energy of the hydrogen atom in the 3p state is -1.51 eV.
Now, the value of L can be calculated as,

For 3p state, l=1

Therefore, the value of L of a hydrogen atom in 3p state is
.
No, that's silly.
You've got your Pfund series where electrons fall down to the 5th level,
your Brackett series where they fall to the 4th level, and your Paschen
series where they fall to the 3rd level. All of those transitions ploop out
photons at Infrared wavelengths.
THEN next you get your Balmer series, where the electrons fall in
to the 2nd level. Most of those are at visible wavelengths, but even
a few of the Balmer transitions are in the Ultraviolet.
And then there's the Lyman series, where electrons fall all the way
down to the #1 level. Those are ALL in the ultraviolet.