AQA GCSE PHYSICS · PAPER 1 · FOUNDATION & HIGHER
Exam Practice: Half-lives, hazards and uses of nuclear radiation
Half-lives, hazards and uses of nuclear radiation · Atomic structure · Lesson 9 of 10 · 16 marks · 17 minutes
|
Name |
|
Date |
|
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 EXPLAIN (3 marks)
Different radioactive isotopes have different half-lives. Explain why radioactive waste with a very long half-life is a problem.
|
|
|
|
|
|
|
|
(Total for Question 1 = 3 marks)
Question 2 EXPLAIN (4 marks)
Technetium-99m is a radioactive isotope with a half-life of 6 hours. It emits gamma radiation. It is injected into a patient so that internal organs can be explored. Explain why technetium-99m is suitable for this use.
|
|
|
|
|
|
|
|
|
|
|
|
(Total for Question 2 = 4 marks)
Question 3 EXPLAIN (3 marks)
In radiotherapy, narrow beams of gamma radiation are directed at a tumour from several different directions. Explain why.
|
|
|
|
|
|
|
|
(Total for Question 3 = 3 marks)
Question 4 COMPARE (2 marks)
Uranium-238 has a half-life of 4.5 × 10⁹ years. Iodine-131 has a half-life of 8 days. State which isotope stays radioactive for longer and give a reason.
|
|
|
|
|
|
(Total for Question 4 = 2 marks)
Question 5 EVALUATE (4 marks)
Some people are worried about using radioactive materials in medicine. Evaluate the risks and benefits of using a radioactive tracer.
|
|
|
|
|
|
|
|
|
|
|
|
(Total for Question 5 = 4 marks)
TOTAL FOR PAPER = 16 MARKS
|
|
Answers and mark scheme
Check your answer only once you have written one.
Question 1 (3 marks)
A very long half-life means the material remains radioactive for a very long time (many thousands or millions of years), so it must be stored safely for a long time.
• Long half-life means it stays radioactive 1 mark
• For a very long time 1 mark
• So it must be stored safely 1 mark
Question 2 (4 marks)
Gamma radiation can pass out of the body so it can be detected outside. It is weakly ionising so causes little damage. A half-life of 6 hours is long enough to complete the scan but short enough that the radioactivity soon decays.
• Gamma passes out of the body 1 mark
• Detected outside the body 1 mark
• Weakly ionising: little damage 1 mark
• Short half-life: decays quickly 1 mark
Question 3 (3 marks)
Where the beams cross at the tumour the dose is high, which destroys the cancer cells. Healthy tissue only receives one beam at a time, so the dose is low and less damage is done.
• High dose where the beams cross at the tumour 1 mark
• Healthy tissue receives low dose 1 mark
• Reduces damage to healthy cells 1 mark
Question 4 (2 marks)
Uranium-238, because its half-life is much longer.
• Uranium-238 1 mark
• Much longer half-life 1 mark
Question 5 (4 marks)
Benefits: organs can be explored without surgery, and diagnosis can be quicker and more accurate. Risks: ionising radiation can damage cells and could cause cancer, but the dose is small and the tracer has a short half-life, so the benefit usually outweighs the risk.
• Benefit described 1 mark
• Risk described 1 mark
• Small dose or short half-life reduces risk 1 mark
• A conclusion 1 mark