GCSE Questions: Radioactivity
Q3.
(a) When atoms of uranium-238 (
) decay they produce a radionuclide called thorium-234 (
).
Thorium 234 (Th-234) decays by emitting beta radiation.
(i) What does beta radiation consist of?
(1 mark)
(ii) Thorium 234 (Th-238) decays to form protactinium 234 (
).
What differences are there between the nucleus of a protactinium-234 atom and the nucleus of a thorium 234 atom?
(2 marks)
(b) The graph shows how the amount of radiation emitted by a sample of the radionuclide uranium-238 changes as time passes.
(i) Use the graph to find the half-life of uranium-238
(3 marks)
(ii) What fraction (or percentage) of the uranium-238 atoms will have decayed after 9 billion years?
(1 mark)
(c) Uranium-238 decays through a long series of intermediate radionuclides to stable atoms of the isotope lead-206 (
).
A sample of igneous rock contains 3 atoms of uranium-238 for every atom of lead-206.
(i) The intermediate radionuclides are not important when estimating the age of the rock. Explain why.
(1 marks)
(ii) Estimate the age of the rock. (You should explain how you obtained your answer).
(3 marks)
(Total 11 marks)
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