Pearson Edexcel International GCSE (9–1) · PHYSICS · Unit
Radioactivity and Particles
123 practice questions
Topics covered
Practice questions
11–15 of 15 · Hard
Question 11
4 marks · Hard
Answer and see the solution →Nuclear fusion is being researched as a possible source of unlimited clean energy on Earth, but it has not yet been achieved on a large scale.
Explain, using scientific ideas, why achieving nuclear fusion on Earth is much more difficult than in the core of stars. Include at least two physical reasons in your answer.
Question 12
4 marks · Hard
Answer and see the solution →A student claims that nuclear fission and nuclear fusion are both potential sources of energy.
Explain the difference between fission and fusion in terms of the nuclei involved and the products formed. Then, describe why fusion produces energy only when light nuclei are used.
Question 13
5 marks · Hard
Answer and see the solution →Scientists want to develop fusion reactors as a future energy source, while fission reactors are already in use. The diagram represents a simplified nuclear reactor core.
A simple nuclear reactor core layout (a)[2 marks]Describe the function of: (i) the moderator (ii) the control rods in a nuclear fission reactor.
(b)[2 marks]Explain why a continuous chain reaction occurs in a fission reactor but not in a fusion reactor, even though both reactions can produce neutrons.
(c)[1 mark]Fusion occurs in stars. State two conditions required for fusion to occur and explain why these are necessary.
Question 14
7 marks · Hard
Answer and see the solution →Nuclear power stations rely on an understanding of both fission and fusion.
(a)[3 marks]Outline how a chain reaction is started and controlled in a fission reactor, and explain why this is necessary for safe operation.
(b)[3 marks]Explain why fusion is the main source of energy in stars but not in current nuclear power stations.
(c)[1 mark]Give one reason why some scientists prefer the idea of fusion over fission as a future energy source on Earth.
Question 15
5 marks · Hard
Answer and see the solution →A nuclear reactor uses uranium-235 as a fuel. The uranium-235 nucleus can undergo fission when it absorbs a neutron. The process produces energy, radioactive daughter nuclei, and more neutrons. Control rods and moderators play key roles in the reactor's operation. Some isotopes in the reactor can also emit gamma radiation.
(a)[2 marks]Describe, using nuclear notation if helpful, the basic process of nuclear fission for uranium-235 and why more neutrons are produced in the process.
(b)[2 marks]Explain how a chain reaction is controlled in a nuclear reactor. Your answer should mention the purposes of control rods and the moderator.
(c)[1 mark]One of the fission products emits gamma radiation. Compare the nature and penetration of gamma radiation with that of beta particles.