Ok, so I find the energy change by doing E of upper state - energy of lower state right? So I get (-0.2) - (-0.5) = 0.3 After I find this energy change, how do i find the decrease in mass? If I use E=mc^2, I plug in 0.3 into E and 1.00794 into m? What am I solving for? I'm confused. Thanks for your help.
As per [itex]E=mc^2[/itex] , Mass is the condensed form of energy . So whenever energy is released from particle , it is accompanied by a small mass change. So calculate the energy change from one state to another , and then equate the energy change with [itex]mc^2[/itex].