of: radioactive nuclei in a prepared sample
is: the time taken for half the nuclei in the sample to decay. [M1.5, P9.1, P9.2]
hence is: the time taken for the activity to halve. [P9.2]
is: a property of radionuclides, unaffected by the physical or chemical environment. [P9.2]
Copyright 1997, The Open University