. A hydrogen atom initially at rest in the n = 3 state decays to the ground state with the emission of a photon. a) Calculate the energy in eV of the emitted photon. b) Calculate the momentum of the emitted photon. c) By conservation of momentum, the atom, as a whole, must be moving after the photon is emitted. Find the kinetic energy in eV of the atom. Note that the atom moves non-relativistically. [Helpful numbers: the mass of a hydrogen atom is 1.008 amu, and 1.0 amu = 931.5 MeV/c2]