[" Radioactivity : "],[" 3.The kinetic energy of an "alpha" -particle which flies out of the nucleus of a Ra "2^(266)" atom in radioactive "],[" disintegration is "4.78" MeV.Find the total energy evolved during the escape of the "alpha" -particle."],[" 4.The positron is a fundamental particle with the same mass as that of the clectron and with a charge "]