An Electron in an Atom Initially Has an Energy 7

Multiple Choice

An electron in an atom initially has an energy 7.5 eV above the ground state energy.It drops to a state with an energy of 3.2 eV above the ground state energy and emits a photon in the process.The momentum of the photon is:

A) 1.7 * 10^-27 kg .m/s
B) 2.3 * 10^-27 kg . m/s
C) 4.0* 10^-27 kg . m/s
D) 5.7 *10^-27 kg . m/s
E) 8.0 * 10^-27 kg . m/s