Tritium (13H^{3}_{1}\text{H}13H) is a radioactive isotope of hydrogen. Hydrogen-1 (11H^{1}_{1}\text{H}11H) is stable.
Explain how an atom of tritium (13H^{3}_{1}\text{H}13H) differs from an atom of hydrogen-1 (11H^{1}_{1}\text{H}11H).
Water in a sealed underground source contains both hydrogen-1 and tritium atoms. In freshly fallen rainwater, the ratio of tritium to hydrogen-1 is 1:1×10181 : 1 \times 10^{18}1:1×1018.
Tritium has a half-life of 12 years.
Describe how the amount of tritium in the sealed underground source decreases with time once it is isolated from the atmosphere.
A sample of water from an underground aquifer is tested and found to have a tritium to hydrogen-1 ratio of 1:8×10181 : 8 \times 10^{18}1:8×1018.
Calculate how many years ago this water was isolated from the atmosphere.
Other radioactive isotopes have very short half-lives.
Suggest a use for a radioactive isotope with a half-life of 10 minutes, and explain why a short half-life is suitable for this use.
484 exam-style questions on CIE IGCSE Physics 5.2 Radioactivity, covering 5.2.1 Background radiation and measuring count rate, 5.2.2a Alpha, beta and gamma emission, 5.2.2b Deflection and ionising effects of nuclear radiation, 5.2.3a Radioactive decay, 5.2.3b Effects of decay on the nucleus and decay equations, 5.2.4a Half-life, 5.2.4b Choosing isotopes for applications, and 5.2.5 Effects of ionising radiation and safety precautions. Each one has a worked solution and a mark scheme showing where the marks go.