Pearson Edexcel International GCSE (9–1) · PHYSICS · Unit
Radioactivity and Particles
123 practice questions
Topics covered
Practice questions
81–90 of 123
Question 81
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 82
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 83
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.
Question 84
1 mark · Easy
Answer and see the solution →State the main process that provides energy in the core of stars such as the Sun.
Question 85
3 marks · Easy
Answer and see the solution →Nuclear fusion involves combining two light atomic nuclei to form a heavier nucleus.
(a)[2 marks]Name the two isotopes of hydrogen most commonly used in nuclear fusion experiments on Earth.
(b)[1 mark]State one particle (not a nucleus) that is released as a product in these fusion reactions.
Question 86
3 marks · Easy
Answer and see the solution →The diagram shows the reaction between a deuterium nucleus and a tritium nucleus.
(a)[2 marks]Explain why a very high temperature is needed for fusion to occur between deuterium and tritium nuclei.
(b)[1 mark]State one reason why fusion reactions are difficult to achieve on Earth, besides temperature.
Question 87
1 mark · Easy
Answer and check →Which of the following statements correctly describes nuclear fusion?
- A.Two light nuclei join to form a heavier nucleus, releasing energy.
- B.A heavy nucleus splits into two lighter nuclei, releasing energy.
- C.An unstable nucleus emits an alpha particle to become more stable.
- D.A neutron is absorbed by a nucleus, causing it to become unstable.
Question 88
1 mark · Easy
Answer and see the solution →State the process that powers the Sun and other stars.
Question 89
1 mark · Easy
Answer and check →Which statement best describes why nuclear fusion requires very high temperatures and pressures?
- A.The nuclei must move slowly enough to combine.
- B.The repulsive forces between nuclei must be overcome.
- C.There must be enough gravity for fusion to occur.
- D.Radioactive waste must be produced by fusion.
Question 90
2 marks · Easy
Answer and see the solution →Describe what happens during nuclear fusion in stars.