Dietary iodine is predominantly the stable isotope iodine-127, whereas medical imaging of the thyroid often utilises the radioactive isotope iodine-131.
Compare the nuclear composition of these two isotopes. State one similarity and one difference between the particles contained within a nucleus of iodine-127 and a nucleus of iodine-131.
81 exam-style questions on Edexcel GCSE Physics 6.1 Atomic structure and isotopes. Each one has a worked solution and a mark scheme showing where the marks go.