Question
The isotope 125B having a mass 12.014 u undergoes β -decay to 126C , 126C has an excited state of the nucleus (125C∗ ) at 4.041 MeV above its ground state. If 125B decays to 126C∗, the maximum kinetic energy of the β-particle in units of MeV is
(1 u=931.5MeV/c2, where c is the speed of light in vacuum).