Pearson Edexcel International GCSE (9–1) · PHYSICS · Unit
Radioactivity and Particles
123 practice questions
Topics covered
Practice questions
1–10 of 15 · Hard
Question 1
3 marks · Hard
Answer and see the solution →A class is designing an experiment to compare the ranges of different types of ionising radiation in air. They list the following possible measurements for their experiment: - The distance from the radioactive source to the detector - The thickness of aluminium sheets placed between the source and detector - The number of decays per unit time measured at the detector For each measurement above, identify and justify the most appropriate unit to use according to the syllabus requirements.
Question 2
2 marks · Hard
Answer and see the solution →In an investigation of half-life, you are told to record the 'interval' for each measurement of activity and to keep the apparatus at the same separation throughout. Name the correct units you would use to record (i) the time interval between measurements and (ii) the separation between the radioactive source and detector. Briefly justify your answers.
Question 3
4 marks · Hard
Answer and see the solution →The isotope oxygen-19 has 8 protons and 11 neutrons. Oxygen-16 is a stable isotope. Explain, using scientific reasoning, why oxygen-19 is less stable than oxygen-16.
Question 4
5 marks · Hard
Answer and see the solution →A nucleus of potassium-40 () decays by emitting a beta minus particle to form a stable isotope.
(a)[2 marks]Write a balanced nuclear equation for this decay, including the atomic and mass numbers of all particles.
(b)[3 marks]Explain, using your answer, what has changed inside the nucleus.
Question 5
5 marks · Hard
Answer and see the solution →Explain, in detail, why nuclei with either far too few or far too many neutrons compared to protons tend to be unstable. In your answer, refer to the balance of forces in the nucleus and the typical changes that such nuclei might undergo to become more stable.
Question 6
5 marks · Hard
Answer and see the solution →A sample contains the isotope chlorine-36, which decays by beta minus emission. After 72,000 years, a scientist finds that only 25% of the original chlorine-36 remains.
(a)[2 marks]Write a balanced nuclear equation for the beta minus decay of chlorine-36. State the names and atomic numbers of the products formed.
(b)[3 marks]Calculate the half-life of chlorine-36. Give your answer to the nearest thousand years.
Question 7
5 marks · Hard
Answer and see the solution →Two isotopes of cobalt are compared in an experiment. Both have atomic number 27, but cobalt-59 is stable, while cobalt-60 is unstable and undergoes beta minus decay.
(a)[2 marks]Explain how the numbers of neutrons affect the stability of cobalt-59 and cobalt-60.
(b)[3 marks]Cobalt-60 has a half-life of 5.3 years. What percentage of a sample will remain after 15.9 years? Show your working.
Question 8
5 marks · Hard
Answer and see the solution →A nuclear power plant uses uranium-235 as its fuel. The process of fission for a single uranium-235 nucleus is represented by the equation:
(a)[3 marks]Explain, step by step, how the products of this reaction lead to the release of energy. In your answer, refer to how the energy is distributed between the different products.
(b)[2 marks]Describe what happens to the neutrons that are produced in this reaction in a working nuclear reactor. Include the roles of the moderator and control rods in your answer.
Question 9
4 marks · Hard
Answer and see the solution →Nuclear fusion is the process that powers stars, while nuclear fission is used in reactor power plants on Earth.
Compare and explain, in detail, why it is much more difficult to start and sustain nuclear fusion reactions on Earth than nuclear fission. Your answer should refer to the forces involved and the conditions needed.
Question 10
5 marks · Hard
Answer and see the solution →A sample of uranium-235 is kept in a laboratory. It is observed that a chain reaction does not start when only a small amount is present.
(a)[2 marks]Explain why a chain reaction cannot be set up in a very small mass of uranium-235, using the concept of critical mass.
(b)[3 marks]Calculate and explain what happens to most of the neutrons that are produced during fission in a sub-critical sample. Suggest two different ways these neutrons are prevented from causing further fission.