A research student is setting up an experiment with a freshly prepared radioisotope sample.
(i) State the law of radioactive decay and define the decay constant.
(ii) Distinguish between the activity of a sample at an instant and the total number of disintegrations that occur in a finite time interval.
(iii) Using qualitative reasoning based on the decay law, explain why treating the activity as constant over several half-lives gives an over-estimate of the number of disintegrations that actually occur in that period.