Actinium is a radioactive element with the chemical symbol Ac\text{Ac}Ac. The proton number for actinium is 89. Actinium-225 is an isotope of actinium that has a nucleon number of 225.
Write the nuclide notation for actinium-225.
Determine the number of neutrons in one nucleus of actinium-225.
The half-life of actinium-225 is 10 days. A sample contains 80 mg of actinium-225.
Calculate the time taken for the mass of actinium-225 in the sample to decay from 80 mg to 5 mg.
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.