A level: Radioactivity Questions

Q4.The radioisotope iodine-131 is used in medicine to treat over-active thyroid glands.

It decays into an isotope of xenon (Xe) by β^– emission with a half-life of 8.1 days.

The xenon subsequently emits a γ ray.

(a) Explain what is meant by:

(i) isotope;

(2 marks)

(ii) half-life.

(1 mark)

(b) Write down the equation which represents the nuclear reaction.

(3 marks)

(c) Calculate the time (in days) for a sample of iodine to decay to 1% of its initial activity.

(4 marks)

(d) State and explain which decay product can be detected outside the body during treatment.

(2 marks)

(Total 12 marks)