Which statement explains the meaning of the half-life of a radioactive source?
half the time taken for the activity of the source to decrease by half
half the time taken for the activity of the source to decrease to zero
the time taken for the activity of the source to decrease by half
the time taken for the activity of the source to decrease to zero
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.