(a)[2]
Explain what radioactive decay means.
(b(i))[1]
State how the random nature of radioactive decay can be inferred from count rate observations.
(b(ii))[1]
A radioactive source has a long half-life so that, over a period of several days, its decay rate stays constant. State the effect, if any, of an increase in temperature on this decay rate.
(b(iii))[2]
Suggest why some radioactive sources may contain traces of helium gas.