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Edexcel International GCSE Physics · Topic Test
Radioactivity
FREE Online Physics GCSE Course55minutes
50marks
9questions
How it works
- Answer each question. Type into the boxes or pick an option, and use paper for working and drawings.
- Press Check my answers at the end of the question. Tick-box and number answers are marked for you.
- For written answers, compare yours with the mark scheme and tick each point you made. We highlight the key words we spot, but you decide, just like an examiner.
You will need: paper, a pen, a pencil, a ruler and a calculator. Your answers save automatically in this browser.
1
Question 1
7 marksAlpha and beta particles may be emitted by unstable nuclei.
(a)(i)
When an unstable nucleus emits an alpha particle, its atomic (proton) number
(1 mark)
Mark scheme
Answer: C decreases by 2
(a)(ii)
When an unstable nucleus emits an alpha particle, its mass (nucleon) number
(1 mark)
Mark scheme
Answer: D decreases by 4
(b)
Compared to a beta particle, an alpha particle
(1 mark)
Mark scheme
Answer: D has less penetrating power
(c)
Describe how a teacher should measure the activity of a radioactive source using a Geiger–Müller detector.
(4 marks)
Mark scheme
Any four of these score (max 4):
2
Question 2
4 marksThese questions are about radioactivity.
(a)
Which of these is measured in becquerel (Bq)?
(1 mark)
Mark scheme
Answer: A activity
(b)
Which of these has a mass (nucleon) number of 4?
(1 mark)
Mark scheme
Answer: A alpha particle
(c)
Which of these is the same as an electron?
(1 mark)
Mark scheme
Answer: B beta particle
(d)
Which of these is the most ionising?
(1 mark)
Mark scheme
Answer: A alpha particle
3
Question 3
5 marksThe table shows the nature of alpha and beta particles.
| Particle | Nature |
|---|---|
| alpha | helium nucleus |
| beta | electron |
Explain why alpha particles and beta particles have different penetrating powers.
(5 marks)
Mark scheme
Any five of these score (the reverse argument about beta also counts) (max 5):
⚠️ Comparisons of speed, velocity or momentum don’t score here. Talk about charge, mass, ionisation and collisions.
4
Question 4
6 marksA teacher investigates the half-life of a radioactive isotope that decays quickly.
(a)
The teacher measures the background activity. Explain how this value should be used in the investigation.
(1 mark)
Mark scheme
Tick each marking point your answer makes:
(b)
Explain what is meant by the term half-life.
(2 marks)
Mark scheme
Tick each marking point your answer makes:
⚠️ Half-life is about half of all the nuclei in a sample, never one nucleus. (“Reactivity” is chemistry, not physics.)
(c)(i)
The graph shows how the activity of a sample of the radioactive isotope changes with time.
Activity–time graph
Use the graph to find the half-life of the isotope.
s
(2 marks)
Mark scheme
Half-life: 56 s (accept 53 – 59 s): from 2400 Bq at 0 s to 1200 Bq
💡 1200 Bq is half the starting activity. Now read across to the curve and down to the time.
💡 That’s two half-lives (2400 → 600 Bq). One half-life takes it from 2400 to 1200 Bq.
💡 Read the time from the graph, not the half-life of strontium in Q5.
Final answer not right? You can still earn method marks. Tick each step you wrote down (max 1):
(c)(ii)
The teacher takes a new reading every 20 s. Suggest why the teacher measures the activity so frequently.
(1 mark)
Mark scheme
Any one of these scores (max 1):
5
Question 5
7 marksAn unstable isotope of strontium has a half-life of 28.8 years.
It is a beta emitter and can be represented by this symbol: 9038Sr
(a)
What is the mass number of this isotope?
(1 mark)
Mark scheme
Mass number: 90
💡 38 is the atomic (proton) number, the bottom number. The mass number is the top one.
💡 52 is the number of neutrons. The mass number counts protons + neutrons.
(b)
A person can absorb strontium atoms, which stay in their bones. Explain why strontium-90 in the bones is a serious health hazard.
(2 marks)
Mark scheme
Any two of these score (max 2):
(c)
When a strontium-90 nucleus emits a beta particle, it decays to form yttrium-90. Complete the equation for this decay.
(2 marks)
Mark scheme
1 mark for 90 and 0 (both needed), 1 mark for −1.
Mass number of Y: 90
Mass number of β−: 0
💡 An electron has almost no mass, so its mass number is 0.
Atomic number of β−: −1 (the minus sign is essential)
💡 Nearly: a beta particle is an electron, with a charge of −1. Check the bottom numbers balance: 38 = 39 + (−1).
(d)
Yttrium-90 is also an unstable isotope. Explain why strontium-90 and yttrium-90 can both be described as isotopes, even though they have different numbers of protons.
(2 marks)
Mark scheme
Any two of these score (max 2):
⚠️ Sr-90 and Y-90 are not isotopes of each other: isotopes of one element share a proton number. Each is an isotope of its own element.
6
Question 6
4 marksIodine-131 is a radioactive isotope that emits beta particles.
The equation for this decay is 13153I → AZXe + 0−1e
(a)
The atomic (proton) number for iodine-131 is
(1 mark)
Mark scheme
Answer: B 53
(b)
The mass (nucleon) number for Xe is
(1 mark)
Mark scheme
The beta particle has mass number 0, so the mass number stays 131.
Answer: D 131
(c)
Iodine-131 is used to treat thyroid cancer. This radioactive isotope is allowed to enter the tumour. Explain why iodine-131 is suitable for this treatment.
(2 marks)
Mark scheme
Any two of these score (max 2):
⚠️ “It is radioactive” or “it emits beta” is in the question, so it scores nothing on its own. Say why beta and iodine suit a tumour.
7
Question 7
6 marksThere are different types of ionising radiation.
(a)
Complete the table to show the properties of each type.
| Type of ionising radiation | Charge | Emitted by |
|---|---|---|
| alpha particle | unstable nuclei | |
| beta particle | − | unstable nuclei |
| gamma ray | 0 |
(2 marks)
Mark scheme
Charge of an alpha particle: (+)2 (accept ++)
💡 4 is the mass number of an alpha particle. Its charge comes from its 2 protons.
💡 An alpha particle is a helium nucleus: 2 protons, so charge +2.
Gamma rays are emitted by: unstable nuclei
💡 Like alpha and beta, gamma comes from an unstable nucleus.
(b)
The diagram shows a machine which makes aluminium foil. The machine uses a radioactive source to measure the thickness of the foil.
Making aluminium foil
The radioactive source emits beta particles. The output from the detector indicates the thickness of the foil.
Explain why beta particles are used, rather than alpha particles or gamma rays.
(3 marks)
Mark scheme
Any three of these score (max 3):
⚠️ Danger and safety don’t score here: the marks are for how much of each radiation gets through the foil.
(c)
The radioactive source contains strontium-90. A strontium-90 nucleus emits a beta (β−) particle. Which of these describes what happens to the strontium-90 nucleus when it emits a beta particle?
(1 mark)
Mark scheme
A neutron changes into a proton and an electron: one more proton, one fewer neutron.
Answer: B the number of protons increases
8
Question 8
8 marksThe diagram shows the main parts of a nuclear reactor.
A nuclear reactor
(a)
Link each part of the reactor with its main function. The first one has been done for you.
Write your three matches on paper (or in the box), then compare them with the answer.
(2 marks)
Mark scheme
How many of your three matches are right?
(b)
State the type of energy released in a fission reaction.
(1 mark)
Mark scheme
Type of energy: kinetic (energy)
💡 The fission products fly apart at high speed: the energy is released as kinetic energy (it heats the reactor later).
(c)
Explain the role of the moderator in a fission reaction.
(2 marks)
Mark scheme
Tick each marking point your answer makes:
and one more for any one of these:
⚠️ Careful: the control rods absorb neutrons. The moderator only slows them down.
(d)
Explain, in terms of neutrons, what is meant by controlled nuclear fission.
(3 marks)
Mark scheme
Any three of these score (max 3):
⚠️ “Control rods block neutrons” doesn’t score. Say they absorb neutrons.
9
Question 9
3 marksA student finds this representation of nuclear fission on a website.
Nuclear fission
Describe what happens when nuclear fission of uranium occurs.
(3 marks)
Mark scheme
Any three of these score (max 3):
⚠️ “Daughter cells” is biology! The fission products are daughter nuclei.
Your results
0 / 50
| Question | Q1 | Q2 | Q3 | Q4 | Q5 | Q6 | Q7 | Q8 | Q9 | Total |
|---|---|---|---|---|---|---|---|---|---|---|
| Out of | 7 | 4 | 5 | 6 | 7 | 4 | 6 | 8 | 3 | 50 |
| Your mark | – | – | – | – | – | – | – | – | – | 0 |
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