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.
144 exam-style questions on CIE IGCSE Physics 5.2.4a Half-life. Each one has a worked solution and a mark scheme showing where the marks go.