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Edexcel IGCSE Physics revision

Radioactivity and particles units questions

Recognise the becquerel as a unit of activity and distinguish a decay rate from a half-life or a number of nuclei.

Edexcel IGCSE Physics Subtopic 7.a

Radioactivity and particles units syllabus

Questions on radioactivity and particles units can test recall, calculations, explanations, diagrams, data handling and practical skills. You should be able to:

  • 7.1 use the following units: becquerel (Bq), centimetre (cm), hour (h), minute (min) and second (s)

How to answer radioactivity and particles units questions

  1. Write the unit symbol exactly and distinguish quantities that use similar-looking units.
  2. Convert prefixes and compound units before substituting values into an equation.
  3. Check that the unit of the final answer matches the quantity asked for.
  4. Use the context of a diagram or calculation to reject units with the wrong dimensions.

Radioactivity and particles units example questions and worked answers

These examples show how information in a diagram, graph or experimental context becomes part of a complete exam answer.

Example 1: Giving a suitable unit for activity

June 2023 (R) · Paper 1P · Question 7(a)(i)

Question 1

Protactinium is an element with several different radioactive isotopes.

Protactinium-234 has a half-life of 6.7 hours.

A sample of protactinium-234 has an initial activity of 800 units.

Give a suitable unit for activity.

Final answer

Becquerel (Bq).

Mark scheme points

  1. M1 Give becquerel or Bq. Kilobecquerel (kBq) and curie (Ci) are also accepted. Only one suitable unit is needed.

Explanation

Activity is the number of radioactive decays per second. One becquerel means one decay per second.

Common mistakes

  • Most candidates recalled a suitable unit. Practise matching activity with Bq; hours measure the half-life, not the activity.

Example 2: Identifying the becquerel

June 2023 · Paper 1P · Question 1(a)

Question 2

This is a question about radioactivity.

Which of these is the unit of activity?

A becquerel
B kilogram
C newton
D pascal

Final answer

A — becquerel (Bq).

Mark scheme points

  1. M1 Select A: becquerel.

Explanation

Activity describes the rate of radioactive decay, and its unit is the becquerel (Bq).

Common mistakes

  • Do not confuse the becquerel with the other options: kilogram is a unit of mass, newton is a unit of force, and pascal is a unit of pressure.

Practise Radioactivity and particles units questions

Build a focused practice set from this part of the Edexcel IGCSE Physics syllabus.

Generate Radioactivity and particles units questions View the Radioactivity and particles topic guide