Answer: 124eV Explanation: Apply Planck - Einstein Relation to calculate the energy of an X-Ray photon that has a frequency of 3.00 x 10^16 Hz and the energy of a photon is proportional to its frequency E= hv where E - the energy of the photon h - Planck's constant, equal to 6.626 x 10^-34 Js v - the frequency of the photon and 1 Hz is equal to 1 s^-1 Thus E= 1.988 x 10^-17J Now convert the energy of photon from joules to eV Therefore we get 1.988 x 10^-17J x ( 1 eV / 1.6022 x 10^-19 J) = 124 eV.