The nucleus 124 55 Cs has a half-life of 30.8 s and a molar mass of 124 g.
(a) How many nuclei will be present if we have a pure initial sample of mass 20 ?g?.
(b) How many nuclei 12455 Cs of are present 3.50 minutes later?
(c) What is the initial activity (decay rate) of the sample?