State which radioactive emission (α\alphaα, β\betaβ, or γ\gammaγ) is: (i) the least penetrating; (ii) the least ionising.
Explain the meaning of the term half-life.
The isotope phosphorus-32 is used in agricultural research. A sample of phosphorus-32 is prepared. The half-life of phosphorus-32 is 14 days14\text{ days}14 days. Determine the fraction of phosphorus-32 remaining in the sample after 42 days42\text{ days}42 days.
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.