1. The problem statement, all variables and given/known data A 191Os nucleus decays via β- emission to an excited state of 191Ir at 171 keV. What is the maximum kinetic energy of the electron on the β spectrum? a) 0.134 MeV b) 0.143 MeV c) 0.171 MeV d) 1.859 MeV 2. Relevant equations 191 Os = 190.960928u 191 Ir = 190.960591u (190.960928u - 190.960591u) * 931.5MeV/u = 0.3139 MeV 0.3139 MeV - 0.171 MeV = 0.143 MeV 3. The attempt at a solution I am unsure if my answer of 0.143 MeV is correct. In my notes it says the maximum kinetic energy is equal to the Q value of the reaction, so I wokred out the Q value above then subtracted the "excited state" value.