(a) What is radioactivity? Outline the parameters that determine the stability of the nucleus? [10 marks] (b) The former FSB officer and alleged Russian spy, Litvenenko, ingested 10ng of 210Po which is an -emitter with a half life of 138,376 days. Predict the daughter isotope from the decay of 210Po and suggest why Litvenenko died 6 weeks later. In your answer outline the biological impact of aparticles and explain why it was so hard to determine. [8 marks] (c) Chelation therapy can be used to treat polonium poisoning. Explain the chelate effect and outline the properties of an ideal chelating agent for use in chelation therapy. [8 marks] (d) Distinguish between the use of radioisotopes as a diagnostic tool and their use in radiotherapy. 123I decays via electron capture and ray emission with a half-life of 13.2hrs. Briefly outline the use of this isotope as a diagnostic tool giving the advantages and disadvantages to both the patient and the clinician. A patient is treated with a diagnostic dose of 123 I. Predict the percentage of the radioactive isotope present after 48hrs. [14 marks]