Nuclei of lithium-7 can absorb high-energy protons and emit neutrons, but they do not undergo fission when they absorb neutrons.
In contrast, uranium-235 nuclei undergo fission when they absorb neutrons, emitting several more neutrons in the process.
Give a reason why a self-sustaining chain reaction can occur in a sample of uranium-235 but not in a sample of lithium-7.
94 exam-style questions on Edexcel GCSE Physics 6.5 Uses and dangers of radioactivity, covering 6.5.1 Uses of radioactivity, 6.5.2 Dangers of ionising radiation and precautions, 6.5.3 Half-life and radiation dangers, 6.5.4 Safety precautions for radiation exposure, and 6.5.5 Contamination and irradiation. Each one has a worked solution and a mark scheme showing where the marks go.