Practise Radioactive contamination. 11 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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Surgical instruments are sterilised by irradiating them with gamma rays. Do the instruments become radioactive?
No
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
(a) What is meant by radioactive contamination? Tick (✓) one box.[1]
The unwanted presence of materials containing radioactive atoms on or in other materials
Exposing an object to nuclear radiation
The decay of an unstable nucleus
The number of decays each second
(b) What is meant by irradiation? Tick (✓) one box.[1]
Exposing an object to nuclear radiation
Radioactive atoms getting onto an object
Heating an object with infrared radiation
An object absorbing light from the Sun
(c) Surgical instruments are sterilised by irradiating them with gamma rays. Do the instruments become radioactive?[1]
(d) Give one precaution a worker could take to avoid being contaminated when handling a radioactive liquid.[1]
Show the answer and mark scheme
(a)Answer: The unwanted presence of materials containing radioactive atoms on or in other materials
(b)Answer: Exposing an object to nuclear radiation
(c)Answer: No
no (an irradiated object does not become radioactive)
(d)Answer: Wear disposable gloves.
wear gloves / protective clothing
use tongs
wear a mask / work in a fume cupboard so that radioactive material is not breathed in
Question 2Medium6 marks
Polonium-210 emits alpha particles.
(a) Explain why a sample of polonium-210 is not very hazardous outside the body, but is extremely hazardous if it gets inside the body.[4]
(b) Explain why a person who has swallowed a radioactive substance is described as contaminated, not irradiated.[2]
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(a)Answer: Outside, the alpha particles are stopped by air or dead skin and never reach living cells. Inside, they are absorbed by nearby living cells, and being strongly ionising they cause severe damage.
outside the body the alpha particles are absorbed by the air / by the outer layer of the skin
so they do not reach living cells
inside the body the alpha particles are absorbed by the (living) cells close to the source
alpha particles are strongly ionising, so they cause a lot of damage to these cells (e.g. to DNA, which can cause cancer)
(b)Answer: The radioactive atoms are now inside the body, so the exposure continues until they decay or are removed.
the radioactive atoms are inside the person's body
so the person keeps being exposed to radiation until the atoms decay or leave the body (irradiation only happens while the person is near a source)
Question 3Hard7 marks
Some foods are irradiated with gamma rays to kill bacteria. This makes the food last longer. Some people think that irradiated food is dangerous to eat.
(a) Explain why gamma rays are used rather than alpha or beta radiation.[2]
(b) A shopper says: ‘I will not eat irradiated food because it will be radioactive.’ Evaluate the shopper's statement.[3]
(c) Explain why food that is contaminated with a radioactive isotope is much more hazardous than food that has been irradiated.[2]
Show the answer and mark scheme
(a)Answer: Gamma rays penetrate the packaging and the whole of the food, so they reach all the bacteria.
gamma rays are very penetrating / can pass through the packaging and the food
so they can reach bacteria throughout the food (alpha and beta would be absorbed near the surface)
(b)Answer: Wrong: irradiation only exposes the food to gamma rays; no radioactive atoms are added, so the food does not become radioactive.
irradiated food does not become radioactive
because the food is only exposed to radiation; no radioactive atoms are added to the food (it is not contaminated)
so the shopper is wrong: the food does not emit radiation after irradiation
(c)Answer: Eating contaminated food puts radioactive atoms inside the body, where they keep emitting radiation.
contaminated food contains radioactive atoms, which would be eaten / get inside the body
the atoms keep decaying and emitting radiation inside the body until they decay or are removed