posted by Tisha .
The energy of the electron in the 2s state is -12.98 eV, the energy in the 3s state -10.84 eV. What is the wavelength of the absorbed photon?
E1 - E2 = h c/(wavelength)
The energy difference (E1 - E2) is 2.14 eV
Change that to Joules and use the equation above.
This is easy stuff. Make an effort.