Practice structured questions - Radioactivity
Simple recall questions are usually worth one mark. They are often have command words like give, state, name or identify. Some questions may ask you to state two things, rather than just one, and will be worth two marks.
Structured questions, with command words such as describe or explain, will be worth two or more marks:
- if you are asked to describe something, you need to give an account but no reason
- if you are asked to explain something, you must give reasons or explanations
More complex structured questions will be worth three to five marks. They include questions with complex descriptions and explanations, questions in which you need to compare and contrast two different things, or calculations with several stages.
The mark schemes given here may show answers as bullet points. This is to show clearly how a mark can be obtained. However, it is important that your answer is written in a logical, linked way.
Learn about command words with Dr Alex Lathbridge
Listen to the full series on BBC Sounds.
Understanding the different command words in your science GCSE exams.
Sample question 1 - Foundation
Question
Matt thinks that keeping your distance from radioactive materials is a good thing.
He writes down his conclusions about two radioactive sources in a table.
| Radioactive material | State | Distance from source | Irradiation risk | Contamination risk |
| A | Solid | 1 m | High | None |
| A | Solid | 4 m | Low | None |
| B | Gas | 1 m | Very high | High |
| B | Gas | 4 m | High | High |
| Radioactive material | A |
|---|---|
| State | Solid |
| Distance from source | 1 m |
| Irradiation risk | High |
| Contamination risk | None |
| Radioactive material | A |
|---|---|
| State | Solid |
| Distance from source | 4 m |
| Irradiation risk | Low |
| Contamination risk | None |
| Radioactive material | B |
|---|---|
| State | Gas |
| Distance from source | 1 m |
| Irradiation risk | Very high |
| Contamination risk | High |
| Radioactive material | B |
|---|---|
| State | Gas |
| Distance from source | 4 m |
| Irradiation risk | High |
| Contamination risk | High |
Describe the difference in the risks for irradiation and contamination for A and B. [4 marks]
OCR Gateway Science, GCE Physics, Paper J249, 2016.
For radioactive material A (solid) the irradiation decreases with distance. Because material A is solid, no contact with the source means there is no contamination risk.
Radioactive material B is a gas so it can move towards a person. Therefore, the gas can be breathed in causing a contamination risk.
Sample question 2 - Foundation
Question
Nuclear radiation can be beneficial or harmful.
Describe one beneficial use of nuclear radiation, and also how nuclear radiation can harm people. [2 marks]
OCR Gateway Science, GCE Physics, Paper B751, June 2015.
Beneficial, any one from:
- smoke detectors
- tracer
- cancer treatment
- diagnosis
- sterilising equipment/food
Harm, any one from:
- damages cells/causes mutations
- causes cancer/tumours
- ionises (cells)
Sample question 3 - Higher
Question
Gamma radiation is used to irradiate cancers in the brain.
Treatment is given for 15 minutes every four days. During treatment, the gamma source is rotated 360° around the head. The patient remains still during treatment.
Each patient receives a certain dose of radiation.
Explain how this treatment reduces damage to healthy cells. [4 marks]
OCR Gateway Science, GCE Physics, Paper J249, 2016 - Higher.
The treatment reduces damage to healthy cells in four ways. Firstly, four days between treatments allows healthy cells to be repaired or replaced.
Secondly, the size of the dose is related to the mass of the patient, age of the patient, size of the tumour and the nature of the tumour.
Thirdly, the rotation of the source reduces damage to healthy cells because it reduces exposure time.
Finally, the patient remaining still will reduce the damage to healthy cells.
Sample question 4 - Higher
Question
The information below shows information on radioactive isotopes.
| Radioactive isotope | Type of radiation | Half-life | Penetration through human flesh |
| A | Alpha | 300 years | 2 mm |
| B | Beta | 7 hours | 60 mm |
| C | Gamma | 7 hours | > 10 m |
| D | Alpha | 9 seconds | 2 mm |
| E | Gamma | 3 years | > 10 m |
| Radioactive isotope | A |
|---|---|
| Type of radiation | Alpha |
| Half-life | 300 years |
| Penetration through human flesh | 2 mm |
| Radioactive isotope | B |
|---|---|
| Type of radiation | Beta |
| Half-life | 7 hours |
| Penetration through human flesh | 60 mm |
| Radioactive isotope | C |
|---|---|
| Type of radiation | Gamma |
| Half-life | 7 hours |
| Penetration through human flesh | > 10 m |
| Radioactive isotope | D |
|---|---|
| Type of radiation | Alpha |
| Half-life | 9 seconds |
| Penetration through human flesh | 2 mm |
| Radioactive isotope | E |
|---|---|
| Type of radiation | Gamma |
| Half-life | 3 years |
| Penetration through human flesh | > 10 m |
a) A doctor injects a patient with isotope C to track blood flow through the body.
Use the data to suggest why the doctor uses isotope C. [1 mark]
b) A doctor implants radioactive isotope A into a patient to treat a localised cancer which is a few mm in size. She intends to remove the isotope in a few weeks.
Use the data to suggest two reasons why the doctor uses isotope A. [2 marks]
c) A doctor wants to irradiate a tumour using gamma rays.
Why does the activity of the source need to be checked before it is used on a patient? [3 marks]
OCR Gateway Science, GCE Physics, Paper J249, 2016 - Higher.
a) Any one from:
- gamma can get out of body
- least amount of time to do damage to the body
- reasonable half-life
b) Any two from:
- alpha has short range
- highest ionising power
- longer half-life than D
c)
To check the activity/intensity/strength of the isotope.
The activity will be continually falling so needs to be monitored.
