(a) Define half-life of a radioactive nuclide.
(b) For an ideal sample containing a very large number of nuclei, explain—without performing any numerical calculation—why the time taken for the sample to fall from its full strength to 50% strength is equal to the time taken for it to fall from 50% strength to 25% strength.
(c) Using your reasoning in part (b), state how the successive time intervals required for a sample to be reduced to 12.5%, 6.25% and 3.125% of its original value are related to the half-life.