AQA GCSE PHYSICS · PAPER 1 · FOUNDATION & HIGHER
Exam Practice: Radioactive decay and nuclear radiation
Radioactive decay and nuclear radiation · Atomic structure · Lesson 4 of 10 · 17 marks · 18 minutes
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Instructions
• Answer all the questions.
• Write your answers in the spaces provided.
• The marks for each question are shown in brackets - use this as a guide to how much to write.
• The answers are on separate pages at the back. Attempt every question before you look at them.
• Answer all questions. Use the mark allocation as a guide to how much to write.
Question 1 STATE (2 marks)
Describe what an alpha particle is and what a gamma ray is.
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(Total for Question 1 = 2 marks)
Question 2 COMPLETE (3 marks)
Complete the sentences. Alpha radiation is stopped by a ______. Beta radiation is stopped by a few millimetres of ______. Gamma radiation is reduced by thick ______.
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(Total for Question 2 = 3 marks)
Question 3 EXPLAIN (3 marks)
A smoke detector contains a source of alpha radiation. Explain why alpha radiation is used and not gamma radiation.
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(Total for Question 3 = 3 marks)
Question 4 EXPLAIN (3 marks)
A factory monitors the thickness of aluminium foil by measuring the radiation that passes through it. Explain why a source of beta radiation is used and not alpha or gamma radiation.
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(Total for Question 4 = 3 marks)
Question 5 EVALUATE (6 marks)
Radioactive sources are used in industry and medicine. Compare the properties of alpha, beta and gamma radiation and evaluate which is best to use as a tracer inside the body.
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(Total for Question 5 = 6 marks)
TOTAL FOR PAPER = 17 MARKS
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Answers and mark scheme
Check your answer only once you have written one.
Question 1 (2 marks)
An alpha particle is two protons and two neutrons (a helium nucleus). A gamma ray is electromagnetic radiation from the nucleus.
• Alpha: two protons and two neutrons 1 mark
• Gamma: electromagnetic radiation 1 mark
Question 2 (3 marks)
sheet of paper; aluminium; lead (or concrete)
• Paper 1 mark
• Aluminium 1 mark
• Lead or concrete 1 mark
Question 3 (3 marks)
Alpha is strongly ionising so it ionises the air to make a current, but is stopped by paper or a few cm of air so it is not a hazard outside the detector. Gamma would pass out of the detector and is weakly ionising.
• Alpha strongly ionising 1 mark
• Stopped by paper or air so safe 1 mark
• Gamma penetrates and weakly ionising 1 mark
Question 4 (3 marks)
Alpha is stopped by the foil so no radiation is detected. Gamma passes through almost unchanged so the thickness makes little difference. Beta is partly absorbed, so the count rate changes as the thickness changes.
• Alpha absorbed completely 1 mark
• Gamma passes through unchanged 1 mark
• Beta partly absorbed so count rate shows the thickness 1 mark
Question 5 (6 marks)
See levels-of-response scheme.
• Level 3 (5 to 6 marks): properties of all three (penetration, range, ionising power), the tracer needs to pass out of the body to be detected outside, and a justified conclusion that gamma is best 5 to 6 marks
• Level 2 (3 to 4 marks): properties of at least two types with some link to use as a tracer 3 to 4 marks
• Level 1 (1 to 2 marks): simple statements about the radiation 1 to 2 marks