IGCSE Physics Safety Precautions Questions and Worked Solutions (5.2.5) | 0625

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IGCSE Physics 0625 · Topic 5.2.5

IGCSE Physics Safety Precautions Questions and Worked Solutions

50 topic-wise practice questions on Safety Precautions (Unit 5: Nuclear Physics), written to the Cambridge IGCSE Physics 0625 syllabus for 2026–2028, each with a step-by-step worked solution.

50 questions19 Core21 Extended10 Challenge121 marksTextbook §5.2 · pp. 260–274
Questions tagged Core are for all candidates (Papers 1 & 3). Questions tagged Extended are Supplement content (Papers 2 & 4). Questions 41–50 are harder Challenge questions. Try each question first, then tap Show solution to check your working.

Topic guide: Safety Precautions

Ionising radiation can damage living cells. Radioactive materials must be stored, used and moved safely. (Extended) Exposure is reduced by limiting time, increasing distance and using shielding.

Key formulas

No equations to learn in this subtopic — time, distance, shielding.

Prerequisite knowledge

  • Types of radiation (5.2.2)
  • Half-life (5.2.4)

Exam tips & common mistakes

  • Name the three methods: time, distance, shielding
  • Match shielding to the radiation type
  • Explain WHY: less time/more distance/shielding → fewer emissions absorbed

Key facts from the syllabus (5.2.5)

  • Effects on living things: cell death, mutations and cancer
  • Storage: lead-lined containers, locked away, labelled
  • Use: tongs, at arm's length, never pointed at people, minimum time
  • Transport: shielded, labelled containers
  • Extended reduce exposure time, increase distance from the source, use shielding to absorb radiation
  • Extended alpha is most dangerous inside the body; gamma is most dangerous outside

Textbook: §5.2 Radioactivity, pp. 260–274

1
Core[3 marks]

State three effects of ionising radiation on living things.

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Method: Cell death, mutation, cancer.

Cell death, mutations and cancer
2
Core[2 marks]

Describe how radioactive sources should be stored.

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Method: Lead-lined containers.

In lead-lined boxes, locked away, labelled
3
Core[2 marks]

Describe how a radioactive source should be handled in a school laboratory.

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Method: Tongs, at arm's length.

With long tongs, held at arm's length, pointing away from people
4
Core[1 mark]

State one way radioactive sources are moved safely.

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Method: Shielded container.

In shielded (lead-lined) containers
5
Core[2 marks]

State why workers with radioactive materials wear film badges (dosimeters).

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Method: Monitor exposure.

To measure their exposure to radiation over time
6
Core[2 marks]

State two safety rules for using radioactive sources in class.

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Method: Minimise exposure.

e.g. use tongs; never point at people; return to store promptly; wash hands; no eating
7
Core[2 marks]

Explain why radioactive waste must be stored for a long time.

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Method: Long half-lives.

Some isotopes have long half-lives and stay dangerous for many years
8
Core[2 marks]

Explain why a gamma source is more dangerous than an alpha source outside the body.

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Method: Penetrates.

Gamma penetrates the skin to reach internal organs; alpha is stopped by skin
9
Core[1 mark]

State the symbol used to warn of radioactive materials.

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Method: Trefoil.

The radiation hazard (trefoil) symbol
10
Core[2 marks]

Explain why pregnant women avoid X-rays where possible.

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Method: Cell damage to foetus.

Rapidly dividing cells of a foetus are more easily damaged by ionising radiation
11
Core[2 marks]

State one way to store radioactive sources safely in schools.

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Method: Lead box.

In a lead-lined box in a locked cupboard
12
Core[2 marks]

State why sources should never be held near the eyes.

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Method: Damage cells.

Radiation can damage eye cells (e.g. causing cataracts)
13
Core[2 marks]

State why food and drink are not allowed in laboratories using radioactive sources.

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Method: Ingestion.

To avoid radioactive material being swallowed
14
Core[2 marks]

State why waste from nuclear power stations is stored underground or in thick containers.

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Method: Shielding, long half-life.

It remains radioactive for a long time and must be shielded from people
15
Core[2 marks]

State how radioactive materials are transported safely.

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Method: Shielded flasks.

In strong, shielded containers (e.g. lead or steel flasks) clearly labelled
16
Core[2 marks]

State three effects ionising radiation can have on living cells.

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Method: Death, mutation, cancer.

Cell death, mutations, cancer
17
Core[2 marks]

Explain why a mutation in a cell can lead to cancer.

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Method: Uncontrolled division.

Damaged DNA can cause cells to divide uncontrollably
18
Core[2 marks]

State why film badges include windows of different materials.

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Method: Identify radiation type.

To find out which types of radiation the worker has been exposed to
19
Core[2 marks]

State one reason why radioactive sources must be labelled.

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Method: Warning.

So people know of the hazard and handle them correctly
20
Extended[2 marks]

Explain how reducing exposure time reduces risk.

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Method: Less dose.

Less time means fewer emissions absorbed, so a lower dose
21
Extended[2 marks]

Explain how increasing distance reduces risk.

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Method: Spread and absorbed.

Radiation spreads out and is absorbed by air, so less reaches the body
22
Extended[2 marks]

Explain how shielding reduces risk.

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Method: Absorbs radiation.

Materials such as lead or concrete absorb radiation before it reaches tissue
23
Extended[2 marks]

Explain why tongs are used rather than fingers to hold a source.

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Method: Distance.

They increase the distance between the source and the hand
24
Extended[2 marks]

Explain why hospital radiographers stand behind a lead screen.

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Method: Shielding.

The lead absorbs X-rays/gamma rays, reducing their exposure
25
Extended[2 marks]

Explain why nuclear power station walls are thick concrete.

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Method: Shielding gamma/neutrons.

Thick concrete absorbs penetrating radiation
26
Extended[3 marks]

Explain why alpha emitters are especially dangerous if swallowed or inhaled.

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Method: Strong ionisation near cells.

Inside the body, alpha particles are absorbed in a very short distance, causing intense ionisation and damage to nearby cells
27
Extended[2 marks]

Explain why staff rotate jobs in areas with radiation.

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Method: Limit exposure time.

To limit each worker's exposure time
28
Extended[2 marks]

Suggest why a source should be returned to its box immediately after an experiment.

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Method: Reduce exposure time.

To minimise the exposure time of everyone in the room
29
Extended[3 marks]

State three methods of reducing exposure to ionising radiation.

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Method: Time, distance, shielding.

Reduce exposure time; increase distance; use shielding
30
Extended[2 marks]

Explain why gamma sources are handled from behind lead screens.

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Method: Shielding.

Lead absorbs gamma radiation, reducing the dose received
31
Extended[2 marks]

Explain why remote-handling tools are used for very strong sources.

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Method: Distance.

They keep the worker far from the source
32
Extended[2 marks]

Explain why limiting exposure time is effective at reducing dose.

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Method: Dose ∝ time.

The dose received is proportional to the time spent near the source
33
Extended[2 marks]

Explain why distance is an effective safety measure for alpha sources.

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Method: Short range.

Alpha particles have a range of only a few cm in air
34
Extended[2 marks]

State the most suitable shielding for beta sources.

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Method: Aluminium/Perspex.

A few mm of aluminium (or thick Perspex)
35
Extended[3 marks]

A worker must handle a gamma source. Suggest three precautions.

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Method: Time, distance, shielding.

Work quickly, use long tongs or remote handling, and work behind a lead screen
36
Extended[2 marks]

Explain why patients receiving radiotherapy may be kept apart from visitors for a short time.

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Method: Reduce others' exposure.

To avoid exposing others to radiation from radioactive material in the patient
37
Extended[2 marks]

Explain why aircraft crew have their radiation dose monitored.

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Method: Cosmic rays.

They receive higher doses from cosmic rays at altitude
38
Extended[2 marks]

Explain why a radioactive source with a short half-life is safer to dispose of.

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Method: Decays quickly.

Its activity falls to safe levels quickly
39
Extended[2 marks]

Explain why alpha radiation from outside the body is relatively harmless.

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Method: Stopped by skin.

It is stopped by the dead outer layer of skin
40
Extended[3 marks]

Compare the hazard of a beta source outside the body and inside the body.

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Method: Penetration vs ionisation.

Outside: it can penetrate skin and damage tissue a few mm deep; inside: it ionises tissue around it, more harmful than outside but less than alpha inside

Challenge questions

Harder, multi-step questions at the top end of the exam. Attempt these once you are confident with the questions above.

41
ChallengeCore[4 marks]

Describe how radioactive sources in a school are stored, used and returned, giving reasons for each precaution.

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Method: Storage and handling.

Stored in lead-lined boxes in a locked cupboard (shielding, security); handled with tongs at arm's length, never pointed at people (distance); returned immediately after use (time); hands washed afterwards
42
ChallengeCore[3 marks]

State three effects of ionising radiation on living cells and explain why high doses are more dangerous.

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Method: Damage.

Cell death, mutations, cancer; more radiation means more cells damaged and a higher chance of serious effects
43
ChallengeCore[4 marks]

Explain why radioactive sources must be kept away from food and why eating is not allowed where sources are used.

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Method: Ingestion.

Radioactive material could be swallowed, placing the source inside the body where alpha/beta cause serious damage
44
ChallengeExtended[4 marks]

Explain how time, distance and shielding each reduce the dose received from a gamma source.

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Method: Three methods.

Less time near it means fewer emissions absorbed; greater distance means the radiation is spread out (and partly absorbed); shielding like lead absorbs the radiation
45
ChallengeExtended[4 marks]

Compare the hazard from alpha, beta and gamma sources outside and inside the body.

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Method: Penetration vs ionisation.

Outside: gamma most dangerous (penetrates), alpha least (stopped by skin). Inside: alpha most dangerous (highly ionising, absorbed by nearby cells), gamma least
46
ChallengeExtended[4 marks]

Explain why nuclear waste with a long half-life is buried deep underground in sealed containers.

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Method: Long-lasting hazard.

It remains radioactive for thousands of years; deep burial and sealing provide shielding and stop it entering water supplies
47
ChallengeExtended[4 marks]

Explain why a radiographer leaves the room or stands behind a screen during an X-ray, but the patient does not need to.

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Method: Cumulative dose.

The radiographer would be exposed many times each day; the patient receives a single small dose and the benefit outweighs the risk
48
ChallengeExtended[3 marks]

Explain why workers who handle radioactive materials wear dosimeters.

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Method: Monitor dose.

To measure the total dose received over time and keep it below safe limits
49
ChallengeExtended[4 marks]

Explain why remote-handling tools and thick lead-glass windows are used in nuclear facilities.

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Method: Distance and shielding.

They allow workers to handle highly active materials from a distance, behind shielding that absorbs radiation
50
ChallengeExtended[4 marks]

A patient is given a gamma tracer with a half-life of 6 hours. Explain why the hospital asks them to avoid close contact with young children for a day.

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Method: Remaining activity.

The tracer remains active for a while; after 24 h (4 half-lives) the activity is 1/16, so close contact is limited until then to reduce others' exposure
All IGCSE Physics topics← 5.2.4 Half-Life6.1.1 The Earth →

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