Q and R are different radioactive isotopes. Q has a different half-life to R. (i) Explain what is meant by the term half-life. (ii) The graph shows how activity of isotope Q and isotope R change with time. Which isotope, Q or R, has the longest half-life? Explain your answer. (b) The table shows information about different elements. Iodine-131 is a radioactive isotope. Iodine-131 decays, emitting a beta (β) particle. Write a balanced nuclear equation for iodine-131 decay. The first part is done for you. 131 53 I →

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Q and R are different radioactive isotopes - OCR Gateway - GCSE Physics (Combined Science) - Question 14 - 2018 - Paper 12

Question 14

Q and R are different radioactive isotopes. Q has a different half-life to R. (i) Explain what is meant by the term half-life. (ii) The graph shows how activity of... show full transcript

Worked Solution & Example Answer:Q and R are different radioactive isotopes - OCR Gateway - GCSE Physics (Combined Science) - Question 14 - 2018 - Paper 12

Step 1

Explain what is meant by the term half-life.

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Answer

Half-life is the average time taken for half of the unstable isotopes in a sample to decay. It indicates how long it takes for the activity of a radioactive substance to decrease to half of its initial value.

Step 2

Which isotope, Q or R, has the longest half-life? Explain your answer.

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Answer

Isotope Q has the longest half-life. This can be determined from the graph, as the activity of Q decreases at a slower rate compared to R. A slower decrease in activity over time indicates a longer half-life.

Step 3

Write a balanced nuclear equation for iodine-131 decay.

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The balanced nuclear equation for iodine-131 decay is:

u} $$ This indicates that iodine-131 decays into xenon-131, emitting a beta particle and an antineutrino.

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