Grade 11 Physics Practice Exam

When a neutron collides with a fissile nucleus, the nucleus undergoes fission: it splits into two smaller nuclei and, crucially, releases additional neutrons. Those emitted neutrons can go on to collide with other fissile nuclei, causing more fissions and potentially creating a self-sustaining chain reaction. The energy released comes mainly from the motion of the fission fragments, with some accompanying gamma radiation, but the defining event is the nucleus splitting and generating more neutrons. The other scenarios—absorption without fission, becoming a photon, or emitting gamma rays only—do not describe the primary outcome that drives a chain reaction.