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Edexcel IGCSE Physics revision

Edexcel IGCSE Physics Radioactivity and particles units questions

Revise the syllabus content for Radioactivity and particles units, learn how to approach common exam questions, and study two worked examples with clear diagrams.

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: Using a Diagram

Question 1

A teacher investigates a sample of radioactive material.

The graph shows their results.

Graph of activity against time (minutes) showing activity decreasing over time (a decay curve). The y-axis ranges up to about 1200 and the x-axis from 0 to 35 minutes.

On the graph, give the unit for activity.

Final answer

becquerel (Bq)

Mark scheme points

  1. M1 Gives the unit of activity as becquerel(s), Bq. A prefix such as kBq is also acceptable.

Explanation

Radioactive activity is measured in becquerels (Bq). Therefore, write Bq beside the activity axis.

Common mistakes

  • Do not give seconds, minutes or hours; these are units of time.
  • Do not confuse the unit of activity with the unit used on the time axis.
  • Nearly three quarters of candidates recalled this unit correctly, so memorise the direct link: activity is measured in becquerels (Bq).

Example 2: Using a Diagram

Question 2

Radon is a gas produced by some types of rocks.
The graph shows how the activity of a sample of radon-220 changes with time.
Graph of activity of radon-220 against time in seconds. The curve decreases from about 700 at time 0 s to around 60 by 200 s. The y-axis is activity with missing unit; the x-axis is time in s.
Complete the graph by adding the missing unit for activity.
activity in

Final answer

activity in Bq (becquerels)

Mark scheme points

  1. M1 Correct unit: Bq or becquerel(s).

Explanation

Activity is measured in becquerels. The correct symbol is written with a capital B and a lower-case q: Bq.

Common mistakes

  • Writing only B instead of Bq.
  • Using incorrect capitalisation, such as BQ, bQ or bq.
  • Giving a time unit such as seconds; seconds are the unit for the horizontal axis, not activity.

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