A photon of an X-ray radiation has a wavelength of 5.50 Å. For the radiation, calculate the (a)frequency in Hertz, (b)the energy in Joules, (c) the energy in electron volts (eV) and (d) the energy in kJ/mol.
I would convert 5.50 A to meters, then
c = frequency*wavelength to make the conversion to frequency.
The others are just conversions. Look up the factors and convert.
Post your work if you get stuck.