AQA GCSE Combined Science: Trilogy Physics Paper 1 (Foundation), June 2025: Question 1
9 marks · Low Demand difficulty · Short Answer
Identify properties of isotopes, define radioactivity and beta radiation, interpret a radioactive decay curve to determine activity, half-life, and age, and state the properties of nuclear radiations.
Practise this questionQuestion
Question text
01 There are different isotopes of the element lead.
01.1 What is the difference between the atoms of different isotopes of lead?
[1 mark]
Tick ( ) one box.
The number of electrons
The number of neutrons
The number of protons
01.2 The isotope lead-210 is radioactive.
What is meant by ‘lead-210 is radioactive’?
[1 mark]
Tick ( ) one box.
Lead-210 forms many different compounds.
Lead-210 has unstable nuclei.
Lead-210 melts at a low temperature.3
01.3 The isotope lead-210 emits beta radiation.
What is beta radiation?
[1 mark]
Tick ( ) one box.
Electromagnetic radiation emitted from nuclei
High speed electrons ejected from nuclei
Particles that consist of two neutrons and two protons4
The paint in an old painting contains the isotope lead-210.
The lead-210 in the paint can be used to estimate the age of the painting.
Figure 1 shows how the activity of the lead-210 in the paint changes with time.
Figure 1
01.4 What was the initial activity of the lead-210 in the paint?
Use Figure 1.
[1 mark]
Activity = 5 kBq
01.5 Calculate the activity of the lead-210 in the paint after one half-life.
[1 mark]
Activity = kBq
01.6 What was the estimated age of the painting when the activity was 10 kBq?
Use Figure 1.
[1 mark]
Age = years
The paint also contains other radioactive substances.
01.7 A scientist removed the other radioactive substances before measuring the activity.
The activity would be greater if the other radioactive substances were not removed.
How would the estimate of the age of the painting be different if the activity
was greater?
Use Figure 1.
[1 mark]
Tick ( ) one box.
The estimated age would be lower
The estimated age would be the same
The estimated age would be greater6
The other radioactive substances in the paint emit different types of radiation.
01.8 Complete the sentence.
Choose the answer from the box.
*05* [1 mark]
alpha beta gamma
The type of radiation with the greatest range in air is .
01.9 Complete the sentence.
Choose the answer from the box.
[1 mark]
alpha beta gamma
The type of radiation that is the least penetrating is .
Mark scheme
Show the mark scheme
Question 1
AO /
Question Answers Extra information Mark
Spec. Ref.
01.1 the number of neutrons 1 AO1
6.4.1.2
AO /
Spec. Ref.
01.2 lead-210 has unstable nuclei 1 AO1
6.4.2.1
AO /
Spec. Ref.
01.3 high speed electrons ejected 1 AO1
from nuclei 6.4.2.1
AO /
Spec. Ref.
01.4 50 (kBq) allow an answer in the range 49 1 AO2
(kBq) to 50 (kBq) 6.4.2.3
AO /
Spec. Ref.
01.5 25 (kBq) allow ecf from question 01.4 1 AO2
6.4.2.3
AO /
Spec. Ref.
01.6 age = 50 (years) 1 AO3
6.4.2.3
AO /
Spec. Ref.
01.7 the estimated age would be 1 AO3
lower 6.4.2.1
– – 8464/P/1F – 6.4.2.3
AO /
Spec. Ref. 7
01.8 gamma 1 AO1
6.4.2.1
AO /
Spec. Ref.
01.9 alpha 1 AO1
6.4.2.1
Total Question 1 9
How to answer it
Atomic Structure, Radioactive Decay & Half-Life
This Foundation-tier question assesses fundamental core knowledge from AQA GCSE Combined Science: Physics (Topic 4.4: Atomic Structure):
- Definition of isotopes and why radioactive substances decay (nuclear instability).
- Nature of beta (β) radiation and properties of alpha (α) and gamma (γ) radiation.
- Extracting data from an activity–time decay graph.
- Calculating activity after one half-life and estimating the age of a sample.
Parts 01.1, 01.2 & 01.3: Fundamental Nuclear Recall
Definitions: Isotopes, Radioactivity, and Beta Radiation
✅ Correct Answers
- 01.1: The number of neutrons [1 mark]
- 01.2: Lead-210 has unstable nuclei [1 mark]
- 01.3: High speed electrons ejected from nuclei [1 mark]
💡 Key Knowledge
- Isotopes: Atoms of the same element with the same number of protons, but a different number of neutrons.
- Radioactive decay: A random process where unstable atomic nuclei emit radiation to become more stable. Chemical bonding or melting point has no effect.
- Beta (β) particle: A fast-moving electron emitted when a neutron in the nucleus turns into a proton.
❌ Common Traps
- Confusing beta particles with electromagnetic radiation (which is gamma) or two protons + two neutrons (which is alpha).
- Assuming radioactivity is a chemical property related to bonding or melting points. Radioactivity is strictly a nuclear phenomenon.
Parts 01.4, 01.5 & 01.6: Half-Life & Graph Skills
Reading the Decay Curve for Lead-210
✅ Correct Answers
- 01.4: 50 kBq (allow 49 to 50) [1 mark]
- 01.5: 25 kBq [1 mark]
- 01.6: Age = 50 years [1 mark]
📐 Step-by-Step Calculations
- Initial Activity (01.4): Find where the curve touches the vertical axis at Time = 0 . The line starts exactly on 50 kBq .
- Activity after 1 half-life (01.5):
Half-life is the time it takes activity to halve:
50 ÷ 2 = 25 kBq - Finding Age at 10 kBq (01.6):
Locate 10 kBq on the vertical (y) axis. Move horizontally across to the curve, then read vertically down to find the time on the horizontal axis: 50 years .
🧠 Exam Technique
- Draw construction lines: Always use a ruler and pencil on the exam paper to draw dashed lines from the axis to the curve and down to the other axis.
- Check axis scales carefully! On this graph, 1 major grid block on the time axis = 10 years (each small square = 2 years).
Part 01.7: Graph Interpretation
Effect of Contaminants on Estimated Age
✅ Correct Answer
The estimated age would be lower [1 mark]
🧠 Why This Happens
- As an object ages, its activity decreases (moves to the right on the graph).
- If other radioactive substances remained in the sample, the measured activity would be artificially higher (e.g. 20 kBq instead of 10 kBq).
- A higher activity corresponds to a point earlier in time (closer to time = 0), leading to an estimate that the painting is younger (a lower age).
❌ Common Misconception
Students often think: "more radiation = older sample". Remember: radioactivity decays over time. The highest activity is at the very beginning (newest).
Parts 01.8 & 01.9: Properties of Nuclear Radiation
Comparing Alpha, Beta, and Gamma
✅ Correct Answers
- 01.8: The type of radiation with the greatest range in air is gamma . [1 mark]
- 01.9: The type of radiation that is the least penetrating is alpha . [1 mark]
💡 Radiation Properties Summary
- Alpha (α): Strongly ionising, least penetrating (absorbed by skin or paper), short range in air (approx. 5 cm).
- Beta (β): Moderately ionising, absorbed by ~5 mm aluminium, range of about 1 metre in air.
- Gamma (γ): Weakly ionising, most penetrating (requires thick lead/concrete), greatest range in air (at least 1 km).
❌ Avoid Mixing Penetration & Ionisation
Range and penetration go together, but they are the opposite of ionising power:
- Most penetrating = Gamma (least ionising)
- Least penetrating = Alpha (most ionising)
Topics
Physics · Chemistry · P4: Atomic Structure · C1: Atomic Structure and the Periodic Table
Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Physics Paper 1 (Foundation), June 2025. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.