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.
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.