Can someone please explain this problem and how I would go about solving it?

Question

When a lyman alpha photon is absorbed by an atom of hydrogen, an electron transitions a) from ground level to the first excited state b) from n=2 to n=3 c) from n=3 to n=4 d) from n=1 to n=3

Answer 1

A Lyman photon is emitted when an electron drops back to level 1.  

Therefore, if will be absorbed by an electron at level 1.  Look for the answer that takes an electron from n=1 to somewhere else.

(actually Lyman alpha would take the electron from 1 to 2.  Lyman beta from 1 to 3, Lyman gamma from 1 to 4, etc.

There is a trick answer (n=1 is the ground state and n=2 is the first excited state).

The amounts of energy between each pair of states is very precise and comes in quanta.  If a photon of a certain level of energy flirts with an electron, the electron will absorb it ONLY if the amount of energy is exactly what the electron needs to reach another state.  No in-between, no giving change (the electron cannot take what it needs and emit the change as a weaker photon).  It is an all-or-nothing affair.

It is possible for an electron to climb by step.  

Absorbs a Lyman alpha to go from n=1 to n=2;  absorbs an H-alpha to go from 2 to 3; absorbs a Paschen-alpha to go from 3 to 4.

Then emits a Lyman gamma to go from 4 to 1 (back to ground state).

However, an electron at n=2 cannot do anything with a Lyman alpha (it does not take it to any existing level, therefore the electron will ignore it).