State what is meant by the binding energy of a nucleus.
A nucleus of uranium‑235 absorbs a neutron and becomes unstable. It then undergoes a fission reaction. One possible reaction is
Determine the number of neutrons produced in this fission reaction.
Data for the binding energies per nucleon for this fission reaction are given in the table below.
Calculate the energy released, in 
, from the fission of one nucleus of uranium‑235.
The isotope xenon‑142 is unstable. The isotope xenon‑132 is stable. Suggest a reason why xenon‑142 is unstable.
.
