Answer the following questions about radioactivity in your own words.
a. (i) Define the activity of a radioactive sample and state its SI unit.
b. (ii) Two different isotopes have equal masses but different half-lives. Explain qualitatively why their activities need not be the same.
c. (iii) A chemist must supply a sample whose activity is 3.7×107Bq. She can choose between isotope A (half-life 10h) and isotope B (half-life 40h). Without performing a detailed numerical calculation, state which isotope will require a larger mass to meet the required activity and justify your choice.