P2 Revision Booklet

Radiation

Medium (Grade C)

Q1.         The pie chart shows the sources of the background radiation and the radiation doses that the average person in the UK is exposed to in one year.
Radiation dose is measured in millisieverts (mSv).

(a)    (i)     What is the radiation dose that the average person in the UK receives from radon gas?
...............................................................................................................
...............................................................................................................
              Radiation dose from radon gas = ................................... mSv
(1)

(ii)      A person may receive a higher than average dose of radiation from background sources.
Suggest two reasons why.
1 ............................................................................................................
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2 ............................................................................................................
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(2)

(b)     Exposure to radon gas can cause lung cancer.
A recent study has compared the risk of getting lung cancer, by the age of 75 years, for cigarette smokers and non-smokers.
The people in the study had been exposed throughout their lives to different levels of radon gas.
A summary of the data produced from the study is given in the table.

 
Exposure to radon gas 	Risk of lung cancer by age of 75	
	Non-smoker 	Smoker	
No exposure 	0.4 % 	10 % 	
Moderate exposure 	1.0 % 	14 % 	
Very high exposure 	1.5 % 	32 %	

(i)     Why were people that have had no exposure to radon gas included in the study?
...............................................................................................................
...............................................................................................................
(1)

(ii)     Using information from the table, what conclusions can be made about exposure to radon gas and the risk of getting lung cancer?
...............................................................................................................
...............................................................................................................
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(2)

(c)     At the moment, the regulations designed to protect people from over-exposure to radiation are based on a model called the ‘linear no-thresholdߣ (LNT) model.
Some scientists believe that the LNT model is too simple.These scientists believe that at low radiation levels a process called ‘radiation hormesisߣ happens.
The graphs show that each model suggests a link between the risk of developing a cancer and exposure to low levels of radiation.

The link between the risk of developing cancer and exposure to low levels of radiation suggested by each of the models is different.
Describe how.
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(2)

(d)     Scientists have conducted experiments in which mice have been exposed to different levels of radiation. The number of mice developing a cancer has then been measured.
Discuss whether it is ethical to use animals in scientific experiments.
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(2)
(Total 10 marks)
 Q2.          (a)     The graph shows how the count rate from a sample containing the radioactive substance cobalt-60 changes with time.

(i)      What is the range of the count rate shown on the graph?
From .................... counts per second to .................... counts per second.
(1)

(ii)     How many years does it take for the count rate to fall from 200 counts per second to 100 counts per second?
Time = .................................................. years
(1)

(iii)    What is the half-life of cobalt-60?
Half-life = .................................................. years
(1)

(b)     The gamma radiation emitted from a source of cobalt-60 can be used to kill the bacteria on fresh, cooked and frozen foods. Killing the bacteria reduces the risk of food poisoning.
The diagram shows how a conveyor belt can be used to move food past a cobalt-60 source.

(i)      Which one of the following gives a way of increasing the amount of gamma radiation the food receives?
Put a tick () in the box next to your answer.
 
Increase the temperature of the cobalt-60 source.		

Make the conveyor belt move more slowly.		

Move the cobalt-60 source away from the conveyor belt.		

(1)

(ii)     To protect people from the harmful effects of the gamma radiation, the cobalt-60 source has thick metal shielding.
Which one of the following metals should be used?
Draw a ring around your answer.
 
aluminium	copper	lead	

(1)

(c)     A scientist has compared the vitamin content of food exposed to gamma radiation with food that has not been exposed.
The table gives the data the scientist obtained when she tested 1 kg of cooked chicken.
 
Vitamin	Food not exposed
to gamma radiation	Food exposed to
gamma radiation	
	Mass in milligrams	Mass in milligrams	
B6	1.22	1.35	
B12	21.00	28.00	
E	3.30	2.15	
Niacin	58.00	55.50	
Riboflavin	2.10	2.25	

Considering only this data, which one of the following is a correct conclusion?
Put a tick () in the box next to your answer.
 
Vitamin content is not affected by gamma radiation.		

Gamma radiation completely destroys some types of vitamin.		

Exposure increased the content of some types of vitamin.		

(1)
(Total 6 marks)
Q3.          (a)    The diagram represents 3 atoms, K, L and M.

(i)      Which two of the atoms are isotopes of the same element?
                                                               .................... and ....................
(1)

(ii)     Give a reason why the two atoms that you chose in part (a)(i) are:
(1) atoms of the same element ............................................................
...............................................................................................................
(2) different isotopes of the same element. .........................................
...............................................................................................................
...............................................................................................................
(2)

(b)     The table gives some information about the radioactive isotope thorium-230.
 
mass number	230	
atomic number	90	

(i)      How many electrons are there in an atom of thorium-230?
                                                         ..................................................
(1)

(ii)     How many neutrons are there in an atom of thorium-230?
                                                          ..................................................
(1)

(c)     When a thorium-230 nucleus decays, it emits radiation and changes into radium-226.

What type of radiation, alpha, beta or gamma, is emitted by thorium-230?
                                                            ..................................................
Explain the reason for your answer.
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(3)
(Total 8 marks)
 
Q4.          (a)     A doctor uses the radioactive isotope technetium-99 to find out if a patient’s kidneys are working correctly.

The doctor injects a small amount of technetium-99 into the patient’s bloodstream.
Technetium-99 emits gamma radiation.
Give two reasons why an isotope that emits gamma radiation is injected into the patient rather than an isotope that emits alpha radiation.
1......................................................................................................................
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2......................................................................................................................
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(2)

(b)     If the patient’s kidneys are working correctly, the technetium-99 will pass from the bloodstream into the kidneys and then into the patient’s urine.
Detectors are used to measure the radiation emitted from the kidneys.
The level of radiation emitted from each kidney is recorded on a graph.
    
(i)      How do the graphs show that technetium-99 is passing from the bloodstream into each kidney?
...............................................................................................................
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(1)

(ii)     By looking at the graphs, the doctor is able to tell if there is a problem with the patient’s kidneys.
Which one of the following statements is correct?
Put a tick () in the box next to your answer.
 
Only the right kidney is working correctly.		
Only the left kidney is working correctly.		
Both kidneys are working correctly.		

Explain the reason for your answer.
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(3)

(c)     The patient was worried about having a radioactive isotope injected into their body. The doctor explained that the risk to the patient’s health was very small as technetium-99 has a short half-life.
(i)      What does the term half-life mean?
...............................................................................................................
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(1)

(ii)     Explain why it is important that the doctor uses an isotope with a short half-life rather than an isotope with a long half-life.
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(2)
(Total 9 marks)
Q5.          The pie chart shows the sources of the background radiation and the radiation doses that the average person in the UK is exposed to in one year.
Radiation dose is measured in millisieverts (mSv).

(a)     (i)      What is the total radiation dose that the average person in the UK receives?
...............................................................................................................
...............................................................................................................
                 Total radiation dose = .................................................. mSv
(1)

(ii)     A student looked at the pie chart and then wrote down three statements.
Which one of the following statements is a correct conclusion from this data?
Put a tick () in the box next to your answer.
In the future, more people will be exposed to a greater proportion of
 
radon gas.		

People that have never had an X-ray get 50% of their radiation dose from
 
radon gas.		

The radiation dose from natural sources is much greater than from artificial
 
sources.		

(1)

(b)     The concentration of radon gas inside a home can vary from day to day. In some homes, the level can build up to produce a significant health risk. It is estimated that each year 1000 to 2000 people die because of the effects of radiation from radon gas.
(i)      It is not possible to give an exact figure for the number of deaths caused by the effects of radiation from radon gas. Why?
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(1)

The table gives data for the radiation levels measured in homes in 4 different parts of the UK. The radiation levels were measured using two detectors, one in the living room and one in the bedroom. The measurements were taken over 3 months.
 
Area of
the UK	Number of homes
in the area	Number of homes
in the sample	Average
radiation
level in
Bq/m3	Maximum
radiation
level in
Bq/m3	
A	590 000	160	15	81	
B	484 000	130	18	92	
C	221 000	68 000	162	10 000	
D	318 000	35 300	95	6 900	

(ii)     Give one reason why the measurements were taken over 3 months using detectors in different rooms.
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(1)

(iii)    Use information from the table to suggest why a much higher proportion of homes were sampled in areas C and D than in areas A and B.
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(2)
(Total 6 marks)
Q6.          The table gives information about the three types of particle that make up an atom.
 
Particle	Relative mass	Relative charge	
Proton	 	+1	
Neutron	1	 	
Electron	very small	–1	

(a)     Complete the table by adding the two missing values.
(2)

(b)     Use the information in the table to explain why an atom has no overall electrical charge.
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(2)

(c)     Uranium has two natural isotopes, uranium-235 and uranium-238.
Uranium-235 is used as a fuel inside a nuclear reactor.
Inside the reactor, atoms of uranium-235 are split and energy is released.
(i)      How is the structure of an atom of uranium-235 different from the structure of an atom of uranium-238?
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(1)

(ii)     The nucleus of a uranium-235 atom must absorb a particle before the atom is able to split.
         What type of particle is absorbed?
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(1)

(iii)     The nucleus of an atom splits into smaller parts in a reactor.
         What name is given to this process?
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(1)
(Total 7 marks)
 Q7.          Some types of food are treated with gamma radiation. Low doses of radiation slow down the ripening of fresh fruit and vegetables while higher doses of radiation kill the bacteria that make the food go off.
(a)     (i)      What is gamma radiation?
...........................................................................................................................
(1)

(ii)     Food packed in crates or boxes can be treated using this method.
Why must a source that emits gamma radiation be used?
...........................................................................................................................
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(1)

(iii)     A suitable source of gamma radiation is the isotope caesium 137.
Complete the following sentence by choosing the correct word from the box.
 
electrons	neutrons	protons	

         An atom of caesium 137 has two more .............................................. than an atom of caesium 135.
(1)

(b)     The diagram shows how a conveyor belt can be used to move food past the radioactive source.

(i)      How do the concrete walls reduce the radiation hazard to workers outside the food treatment area?
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(1)

(ii)     Suggest one way that the dose of radiation received by the food could be increased other than by changing the radioactive source.
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(1)

(c)     Some people may not like the idea of eating food treated with radiation.

(i)      What evidence could a food scientist produce to show that food treated with radiation is safe to eat?
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(2)

(ii)     The diagram shows the sign displayed on food treated with radiation.

         Why is it important for people to know which foods have been treated with radiation?
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(1)
(Total 8 marks)
Q8.          The detector and counter are used in an experiment to show that a radioactive source gives out alpha and beta radiation only.

          Two different types of absorber are placed one at a time between the detector and the source. For each absorber, a count is taken over ten minutes and the average number of counts per second worked out. The results are shown in the table.
 
Absorber used	Average counts per second	
No absorber	33	
Card 1 mm thick	20	
Metal 3 mm thick	2	

          Explain how these results show that alpha and beta radiation is being given out, but gamma radiation is not being given out.
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(Total 3 marks)
 
Q9.          (a)     The diagram shows three different boxes and three radioactive sources. Each source is stored in a different box.

          Draw lines to show which source should be stored in each box so that the risk of radiation leakage is a minimum.
(2)

(b)     A leak in an underground oil pipe can be found by injecting a radioactive isotope into the oil. The ground is then tested with a radiation detector and counter.

(i)      State the type of detector used. 
..........................................................................................................................
(1)

(ii)     Complete the sketch graph to show how the reading on the detector will change as it passes along the ground above the pipe.
(1)

(c)     Gamma radiation can be used to kill cancer cells inside a person’s head. During the treatment the patient is kept perfectly still while the source of gamma radiation moves in a circle.

(i)      Why is a source of gamma radiation the most suitable for this treatment?
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(1)

(ii)     Suggest why a moving source of radiation is used rather than one which is kept stationary.
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(2)

(iii)     Gamma radiation is an electromagnetic wave. Give two properties common to all electromagnetic waves.
1 .......................................................................................................................
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2 .......................................................................................................................
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(2)
(Total 9 marks)
Q10.          (a)     A radioactive source can give out three types of emission:
          alpha particles
beta particles
gamma radiation.
          The diagram shows the paths taken by the radiation emitted by two sources, X and Y.

What types of radiation are emitted by each of the sources?
Source X emits ............................................................................................................
Source Y emits ............................................................................................................
(2)

(b)     The diagram shows a disposable syringe sealed inside a plastic bag. After the bag has been sealed the syringe is sterilised using radiation.

Explain why radiation can be used to sterilise the syringe.
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(3)
(Total 5 marks)
 Radiation-Mark scheme
M1.         (a)       (i)     1.25 (mSv)
1

(ii)     any two from:
•        (frequent) flying
accept stated occupation that involves flying
•        living at altitude
•        living in areas with high radon concentrations
accept a specific area, eg Cornwall
•        living in a building made from granite (blocks)
•        having more than the average number of X-rays
or
having a CT scan
accept more medical treatments
•        working in a nuclear power station
accept any suggestion that could reasonably increase the level from a specific source
2

(b)    (i)       to be able to see the effect of exposure (to radon gas)
or
as a control
accept to compare (the effect of) exposure (with no exposure)
1

(ii)     increased levels of exposure increases the risk (of developing cancer)
accept exposure (to radon gas) increases the risk
1

smoking increases the (harmful) effect of radon
answers that simply reproduce statistics are insufficient
1

(c)     LNT model – risk increases with increasing radiation (dose) level
accept in (direct) proportion
accept low doses increase the risk
1

Radiation hormesis - low radiation (dose) levels reduce the risk
1

(d)     two valid points made – examples:
•        animals have no choice and so should not be used
•        should not make animals suffer
•        better to experiment on animals than humans
•        experiments lead to a better understanding / new knowledge
•        experiments may lead to health improvement / cures for humans
results for animals may not apply to humans is insufficient
2
[10]

M2.         (a)      (i)      200 to 50
accept either order
1

(ii)     5.3
accept values between 5.2 and 5.4 inclusive
1

(iii)     5.3
accept values between 5.2 and 5.4 inclusive
ortheir (a)(ii)
1

(b)     (i)      Make the conveyor belt move more slowly
1

(ii)     lead
1

(c)     Exposure increased the content of some types of vitamin.
1
[6]
 M3.         (a)      (i)     K and L 
both answers required either order
1

(ii)     (1) same number of protons
accept same number of electrons
accept same atomic number
1

(2) different numbers of neutrons
1

(b)     (i)     90
1

(ii)     140
1

(c)     alpha (particle)
reason may score even if beta or gamma is chosen
1

mass number goes down by 4or
number of protons and neutrons goes down by 4
or
number of neutrons goes down by 2
candidates that answer correctly in terms of why gamma and beta decay are not possible gain full credit
1

atomic / proton number goes down by 2or
number of protons goes down by 2
accept an alpha particle consists of 2 neutrons and 2 protons for 1 mark
accept alpha equals 42He or 42α for 1 mark
an alpha particle is a helium nucleus is insufficient for this mark
1
[8]
 M4.          (a)     gamma will pass through the body
it refers to gamma
oralpha will not pass through the body
answers must relate to the body
accept skin for body
1

gamma is only slightly ionising
accept gamma causes less damage to cells / tissue
or
alpha is heavily ionising
do not accept gamma causes no damage to cells
less harmful is insufficient
1

(b)     (i)      (both graphs show an initial) increase in count-rate
accept both show an increase
1

(ii)     only the right kidney is working correctly
1

any two from:
if incorrect box chosen maximum of 1 mark can be awarded
reference to named kidney can be inferred from the tick box
•        count-rate / level / line for right kidney decreases (rapidly)
it decreases is insufficient
•        count-rate / level / line for left kidney does not change
it does not change is insufficient
•        radiation is being passed out / into urine - if referring to right kidney
•        radiation is not being passed out - if referring to the left kidney
2

(c)     (i)      time taken for number of nuclei to halve
or
time taken for the count-rate to halve
1

(ii)     short half-life – the level of radiation (in the body) decreases rapidly
it refers to short life isotope
1

to a safe / very small levelora long half-life – the radiation remains in the body / for a long time
level of radiation remains high
answers in terms of damage eg cancer are insufficient
1
[9]
 M5.         (a)      (i)     2.5
1

(ii)     The radiation dose from natural sources is much greater
than from artificial sources.
1

(b)     (i)      other factors may be involved
accept a specific suggestion
eg they may be exposed to other types of radiation
accept cannot be sure (in many cases) that the cause of death is radon (poisoning)
1

(ii)     any one from:
•    different concentrations in different rooms
•    to average out daily fluctuations
accept to find an average
accept to make the result (more) reliable / valid
do not accept to make more accurate on its own
1

(iii)   average level (much) higher (in C and D)
accept converse
1

some homes have very high level (in C and D)
accept maximum level in A and B is low
ormaximum level in some homes (in C and D) is very high 
accept higher radiation levels (in C and D) for 1 mark
1
[6]
 M6.          (a)     
 
Particle	Relative Mass	Relative charge	
Proton	1	 	
Neutron	 	0	

accept one, accept +1
do not accept –1 
1

accept zero
do not accept no charge/ nothing/neutral unless given with 0
1

(b)     equal numbers/amounts of protons and electrons
1
          protons and electrons have equal but opposite charge
accept protons charge +1 and electron charge –1
accept (charge) on proton
cancels/balances (charge) on electron
accept positive (charges) cancel out the negative(charges)
neutrons have no charge is neutral
do not accept total charge of protons, electrons (and neutrons) is 0 unless qualified
1

(c)     (i)      (3) fewer neutrons
accept lower/ smaller mass number
do not accept different numbers of neutrons
any mention of fewer/more protons/electrons negates mark
accept answers in terms of U-238 providing U-238 is specifically stated i.e. U-238 has (3) more neutrons
1

(ii)     neutron
1
(iii)     (nuclear) fission
accept fision
do not accept any spelling that may be taken as fusion
1
[7]
 M7.          (a)     (i)      electromagnetic (wave / radiation)
accept em (wave / radiation)
ignore reference to frequency
1
(ii)     gamma can penetrate the crate / box / packaging
accept converse (but must relate to both alpha and beta)
ignore just gamma radiation kills bacteria
accept can get through to food
1
(iii)     neutrons
1

(b)     (i)      absorb gamma / radiation
accept it stops / reduces the radiation
1
(ii)     any one from:
•        slow down the conveyor belt
•        food does more than one circuit
•        stay on the conveyor belt longer
•        food closer to the source / radiation
ignore larger doses / use more of the source
ignore thinner packaging
1

(c)     (i)      idea of testing food on humans / animals
1
no (measured) ill effects or monitor their health
accept monitor people that have eaten the food
accept a measurement / comparison for 1 mark
eg measure the amount of radiation in treated food
comparison plus a reason for the comparison would get 2 marks
eg idea of measuring level of radiation in treated food with no
measurable increase in level = 2 marks or comparing it to
untreated food = 2 marks
1
(ii)     so can make own decision about eating or not eating treated food
accept may be against their religious / moral views
accept some people prefer food that hasn’t been tampered with
ignore in case they don’t like the idea of eating treated food
accept don’t want to eat treated food
ignore might be allergic to the food
eg think it will give them cancer = 0 marks
think it will give you cancer so I need to know so that I can choose = 1 mark1
1
[8]
M8.          answers must be comparative
accept converse answers throughout
          alpha: the count rate is (greatly) reduced
by the card or the card absorbs alphas but not betas
accept paper for the card
1

          beta: the count rate is (greatly) reduced by the metal or the thin metal absorbs
alphas and betas or the thin metal absorbs all of the radiation (from the source)
accept aluminium for the metal
1
          gamma: would pass through the thin
accept aluminium for the metal
          metal but count rate is background or no radiation passing through or a higher
reading would be recorded or to reduce the count to 2 would require much
more than 3 mm of metal
accept lead / aluminium for the metal
1
[3]
 M9.          (a)     all 3 correct
          
Gamma source            Beta source           Alpha source
allow 1 mark for one or two possible links
no marks for more than one line from a source or to a box
2

(b)     (i)      geiger-müller (tube)
accept G-M (tube)
accept geiger tube or geiger counter
1

(ii)     steady line rising then falling at leak

must be one peak only
1

          (c)     (i)      can penetrate (skull or head)
accept goes through body
accept most penetrating
do not accept strongest
do not accept can penetrate skin
1

(ii)     cancer cells receive full dose or more radiation
accept healthy cells not damaged
1
         healthy or other cells receive low dose only
do not accept it is safer
1

(iii)     any two properties from:
•        travel through a vacuum
do not accept they are an energy form
•        travel at same speed in air or
vacuum
•        can be diffracted
treat as a list ignoring 1 and 2
•        can be reflected
•        can be refracted
•        travel in straight lines
•        all transverse
•        can be polarised
•        transfer energy
2
[9]
M10.          (a)     X emits beta
accept β
1
Y emits alpha, beta, gamma
must have all three accept α, β, γ
1

(b)     gamma
accept beta and gamma
any mention of alpha loses first mark
1
radiation can penetrate (the plastic)
1
          kills bacteria or microbes or micro-organisms or viruses
not germs
1
[5]