A small amount of technetium-99m is spilled on a hospital floor. Technetium-99m has a half-life of 6 hours. The activity of the spill is 3200 Bq3200\ \text{Bq}3200 Bq just after it happens.
Calculate the activity of the spill 24 hours later.
On another day, some caesium-137 is spilled on the floor with the same activity of 3200 Bq3200\ \text{Bq}3200 Bq. Caesium-137 has a half-life of 30 years. The hospital closes off the area of the technetium-99m spill for a few days. The caesium-137 spill must be cleaned up straight away. Explain the difference in the way the two spills are dealt with.
A worker says: 'After 10 half-lives there will be no radioactive technetium-99m nuclei left in the spill.' Evaluate this statement.
48 exam-style questions on OCR GCSE Physics 6.2 Uses and hazards, covering 6.2.1 Contamination and irradiation, 6.2.2 Half-life and radiation hazards, 6.2.3 Medical uses of nuclear radiation, 6.2.4 Nuclear fission and chain reactions, and 6.2.5 Nuclear fusion. Each one has a worked solution and a mark scheme showing where the marks go.