Answer:
2.55 eV is absorbed.
Explanation:
The energy of the nth state of hydrogen atom is,
[tex]E_{n}=-\frac{13.6}{n^{2} }[/tex]
Now energy for the second state is,
[tex]E_{2}=-\frac{13.6}{2^{2} }\\E_{2}=-3.4eV[/tex]
Now energy for the fourth state is,
[tex]E_{4}=-\frac{13.6}{4^{2} }\\E_{4}=-0.85 eV[/tex]
Now energy required to go from 2nd state to 4th state is,
[tex]hf+E_{2}=E_{4}\\ hf=E_{4}-E_{2}[/tex]
Therefore,
[tex]hf=-0.85eV-(-3.4eV)\\hf=2.55eV[/tex]
Therefore, 2.55 eV energy is absorbed by the hydrogen atom to from n=2 state to n=4 state.
