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3 marksHalf-life

CSEC Physics · 1998 · Paper 2 · Question 4(c)(iv)

The radioactive isotope of iodine, 131_53 I, has a half-life of 8 days and is used to study blood circulation.

Calculate after how many days 7/8 of a sample of 131_53 I will have decayed.

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Other parts of this question

  1. 4(a)Describe how a radioactive isotope is used as a tracer in the human body.[2 marks]
  2. 4(b)Give TWO reasons why nuclei that emit only alpha-particles are NOT normally used as medical tracers in the human body.[2 marks]
  3. 4(c)(i)Explain what is meant by the half-life of an isotope.[1 mark]
  4. 4(c)(ii)Give the symbol for another possible isotope of iodine.[2 marks]
  5. 4(c)(iii)Explain why a half-life of 8 days is suitable for medical uses compared to available isotopes with half-lives of 20 seconds and 2 years.[2 marks]
  6. 4(d)Write a balanced nuclear equation for the decay of 131_53 I into xenon (Xe), emitting a beta-particle and gamma-radiation.[2 marks]

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