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.
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.