An accidental spill of the radioisotope tritium, 13H^3_1\text{H}13H, occurs in a research laboratory. After 49.2 years49.2\text{ years}49.2 years have passed, the quantity of tritium present is 25.0% of its original level in some areas, but in others, the standard calculations are needed. For this spill, after 49.2 years49.2\text{ years}49.2 years, the overall average level of tritium present is 6.25% of its original level.
What is the half-life of tritium?
9.8 years9.8\text{ years}9.8 years
12.3 years12.3\text{ years}12.3 years
16.4 years16.4\text{ years}16.4 years
24.6 years24.6\text{ years}24.6 years
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.