1. The problem statement, all variables and given/known data 1) In a sequential process, U(235,92) plus a neutron forms the compound nucleus [U(236,92)]* which then fissions; the fissions then produces decays. If the initial fission fragments are Ba(143,56) and Kr(90,36), illustrate a process leading to the final stable nuclei. 2. Relevant equations 3. The attempt at a solution I have the solution, but I am unable to understand it. They say that both Barium and Krypton undergoes negative beta decays 4 times. The initial process is: U(235,92) + 1 neutron ---> [U(236,92)]* ---> Ba(143,56) + Kr(90,36) + 3 neutrons The final reaction is: U(235,92) + 1 neutron ---> [U(236,92)]* ---> Nd(143,60) + Zr(90,40) + 3 neutrons + 8 electrons + 8 antineutrinos Why can’t alpha decay take place instead of beta decay? I think it is because the former takes place in isotopes having mass number greater than 200? Also, in such questions how do they say that beta decay takes place only 4 times after which a stable nuclei is obtained?