Name: _______________________________________________
P2 Topic 6 Radioactivity Foundation
Date:
Time: 27 minutes
Total marks available: 27
Total marks achieved: ______
Questions
Q1.
Everyone is exposed to background radiation. Some of this radiation comes from natural sources.
(a) (i) One example of a source of background radiation that does not occur naturally is radiotherapy.
State one other source of background radiation that does not occur naturally.
(1)
..............................................................................................................................................
..............................................................................................................................................
(ii) Radon gas is a natural source of background radiation.
In some parts of the country, a lot of the background radiation comes from radon gas.
Explain why there is no radon gas in some other parts of the country.
(2)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
(b) Technetium-99 is one of the radioactive isotopes in nuclear waste.
The graph shows the decay curve for technetium-99.
(i) Use the graph to show that the half-life of technetium-99 is about 200 000 years.
(2)
(ii) Technetium-99 emits beta particles.
Give one reason that beta particles can cause harm to people.
(1)
..............................................................................................................................................
..............................................................................................................................................
*(c) There are many radioactive isotopes in nuclear waste.
Technetium-99 is just one of these isotopes.
People are worried about how we should deal with nuclear waste.
Explain why it is difficult to deal with nuclear waste safely.
(6)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
(Total for Question is 12 marks)
Q2.
* Used nuclear fuel is removed from a reactor for reprocessing.
The workers who remove the fuel are at risk.
Explain how the safety precautions the workers take help to reduce the risks.
(6)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
Q3.
(a) A student watches a radioactivity demonstration.
The demonstration uses this arrangement.
The teacher puts different materials in the holder.
Then she measures the radiation entering the detector.
Here are the results.
material in the holder
radiation entering detector
(counts per minute)
nothing (only air)
paper
aluminium
thick lead
121
17
17
17
(i) Complete the sentence by putting a cross (
The radiation from the source is
) in the box next to your answer.
(1)
A alpha particles
B beta particles
C gamma rays
D X-rays
(ii) The teacher returns the radioactive source to the box.
Suggest why the box is lined with lead.
(1)
..............................................................................................................................................
..............................................................................................................................................
(iii) The counter still gives a reading.
The teacher says this is caused by background radiation.
State one source of background radiation.
(1)
..............................................................................................................................................
(iv) The teacher takes precautions to protect her students from the radiation emitted by the
radioactive sources.
State two suitable precautions that protect the students.
(2)
..............................................................................................................................................
..............................................................................................................................................
(b) Radon is a radioactive gas which emits alpha particles.
(i) A sample of air contains 6 mg of radon.
Radon has a half-life of 4 days.
Calculate the mass of the radon remaining after 8 days.
(2)
..............................................................................................................................................
(ii) Some places have rocks which release radon gas.
Explain why people living in these places may have an increased risk of long-term health problems.
(2)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
(Total for Question is 9 marks)
Examiner's Report
Q1.
(a)(i)
Many candidates did not appreciate that the question asked for a source of background radiation that
does not occur naturally, which ruled out cosmic rays, food, etc. This question also showed that a
significant number of candidates believe that chemotherapy is radioactive rather than being treatment by
drugs. The most frequently seen correct answer was X-ray (machines).
(a)(ii)
The fact that radon gas originates in granite rocks was known by surprisingly few candidates. However, if
the origin was known then it easily explained why some parts of the country did not have radon and this
gave candidates the opportunity of scoring both marks.
Results Plus: Examiner Comments
Power plants were quite often believed to be the origin of radon gas. No marks were awarded.
Results Plus: Examiner Comments
This is a rare example where 1 mark was awarded. The candidate knows the origin of
radon gas but does not explain why it is not found in some parts of the country.
(b)(i)
The majority of candidates were able to score 2 marks. It was unusual for candidates to draw two
horizontal lines to the curve at appropriate values of the activity and then show that by taking
lines from the curve to the y-axis that the half-life was about 200 000 years. Most candidates
took half the activity between 700 Bq and 800 Bq and drew a horizontal line to meet the curve
and then a vertical line to the x-axis indicating the half-life.
Results Plus: Examiner Comments
This answer gained 2 marks for showing the half-life is about 200 000 years, having
started the horizontal line from 760 Bq.
Results Plus: Examiner Comments
This answer gives additional information indicating that half the initial activity is used to
determine the half-life and was awarded 2 marks.
Results Plus: Examiner Comments
This response only scored 1 mark, as the line from the curve to the x-axis does not
meet the line from the y-axis and gives a value which is out of tolerance.
Results Plus: Examiner Tip
Ensure that lines are drawn accurately and if an incorrect line is replaced indicate
clearly which line is to be marked.
(b)(ii)
A disappointing number of candidates could not offer one of the acceptable answers, either
because they gave a general description of the penetration of beta particles rather that relating
the answer to people (as requested in the question) or their answers were incomplete.
Results Plus: Examiner Comments
This answer needs to be extended to explain what is likely to be mutated. The mark
was not awarded.
Results Plus: Examiner Tip
Make sure your answer provides a complete explanation.
Results Plus: Examiner Comments
An acceptable answer would be that beta particles can cause cancer. This answer does
little more than repeat the stem of the question therefore the mark was not awarded.
Results Plus: Examiner Comments
This answer is not related to people and therefore did not score a mark.
(c)
Although there has been an improvement in the way candidates answer this type of question,
many of them struggled to answer it in a coherent way. The best responses mentioned one or
more properties of nuclear waste and then linked them to a problem caused as a result of these
properties before going on to suggest one or more solutions.
Less able candidates mentioned that nuclear waste was harmful to humans or named a method
for dealing with it. It appeared that some candidates may have felt that they needed to fill all the
space available because they repeated the same point in different words.
Results Plus: Examiner Comments
This answer makes the point that nuclear waste is buried under ground. This is a Level
1 response and was awarded 2 marks.
Results Plus: Examiner Comments
This answer includes the point that nuclear waste has a long half-life. One isolated point
is made; this is a Level 1 response and it scored 2 marks.
Results Plus: Examiner Comments
This answer gives detail on why it is difficult to get rid of nuclear waste, the problems it
can cause and it also gives a property of nuclear waste, ie that it has a long half-life. It is
a coherent account linking facts. It is a Level 3 response and was awarded all 6 marks.
Results Plus: Examiner Tip
Try to link facts together using 'because ' or 'therefore'.
Results Plus: Examiner Comments
This answer explains how nuclear waste can be treated and links this to the harm it can
cause. It is a Level 2 response and was awarded 4 marks.
Q2.
No Examiner's Report available for this question
Q3.
(a) (ii)
Many candidates were successful with this question but very few (if any) used the word absorb,
and ionising was used even less. A few candidates thought that lead was a good conductor and
that this was important in this context. A significant number did not make a creditworthy response
as they referred to the source itself not being able to penetrate.
About two thirds of candidates scored this mark.
A common response
Results Plus: Examiner Comments
Answers stating that all the radiation was stopped were acceptable at this level in the
paper
This response contains two non-scoring points.
Results Plus: Examiner Comments
Many candidates confused sources with a type of radiation
(a) (iii)
Many candidates were successful and the most common answer was Radon. Of those that were
not, the majority named a type of radiation rather than a source. A few were not specific enough
and just wrote 'Nuclear' as their answer. Some candidates thought the question referred to the
lead lined box or the experiment specifically and so answered to the effect of 'left-over radiation
from the box'. Too many gave microwaves or mobile phones and some confused cosmic
background radiation (or big bang) with cosmic rays.
Only 50% of candidates scored this mark.
An example of the most common correct response.
Results Plus: Examiner Comments
radon is acceptable for radon gas.
An example of an incorrect response.
Results Plus: Examiner Comments
Microwaves (perhaps linked to CMBR) and mobile phones were other common
non-scoring responses.
(a) (iv)
A minority achieved both marks for this question. Of those that did not, many concentrated on
safety of the demonstrator, general lab safety items such as goggles and gloves or they made
the same point in two different ways. Some thought that "students touching the sources" was
acceptable provided they washed their hands after touching.
35% of candidates scored both marks and 44% scored one mark.
This response scored both marks.
Results Plus: Examiner Comments
'Do not get too close' is acceptable for keeping students at a safe distance.
Weaker candidates often gave the same point in both answer spaces.
Results Plus: Examiner Comments
Both points refer to keeping students at a safe distance.
(b) (i)
Many candidates had a poor grasp of the meaning of half-life. Although 30% gained both marks,
few showed a calculation to give the number of half-lives. A small number tried to calculate the
mass having gone through 8 half-lives. A lot thought that there were 6mg after 4 days and
therefore only took this value through 1 half-life. As in 1(b) the lack of working meant that credit
could not be given for 3mg which could have been obtained by using an incorrect method.
Only 15% scored 1 mark.
A common response with no working.
Results Plus: Examiner Comments
Encourage students to show working.
Responses scoring both marks usually gave clear evidence of their working
Results Plus: Examiner Comments
A good example of how to set out working.
(b) (ii)
Most candidates managed to get 1 ( 43% of candidates) or 2 (14% of candidates) marks for this
question, most commonly by saying the gas could be inhaled or cause cancer. Decay or
ionisation of lung cells was rarely seen. Some indicated 'damage to cells' but many answers
were vague and referred to damage to the body or just repeated the question.
A typical one mark response.
Results Plus: Examiner Comments
Cancer scores one mark.
One of the less common 2 mark responses.
Results Plus: Examiner Comments
Marks are scored for 'inhaling gas' and 'cancer'.
Mark Scheme
Q1.
Answer
(a)(i)
(a)(ii)
(b)(i)
(b)(ii)
any one of
X-ray (machines) /
smoke alarms/
nuclear/ radioactive
waste
(1)
an explanation
linking: comes from
granite / rocks (1)
none/ less of these
(rocks) in some
areas (1)
suitable lines on
graph to show
halving after about
200 000 years (2)
 horizontal line at
750 +or –50 Bq on
y-axis to curve (1)
 meeting (by eye)
vertical line from
x-axis between
190,000 years
and 230,000 years
(1)
any one of

penetrates/passes
through the skin (1)
 ionises (1)
 damages tissue/
Acceptable
answers
nuclear weapons
(tests) nuclear power
plants (medical)
tracers/technetium
in some
areas/Cornwall/Aber
deen the second
mark is dependent
on the first.
use of data from
graph to show
halving after about
200 000 years
1500/2 =750(Bq) or
1600/2=800(Bq)
gives a half-life of
210,000 +or- 20 000
(years)
Mark
(1)
(2)
(2)
(1)
cells/DNA (1)
 mutates
cells/DNA(1)
 causes
cancer(1)
QWC
*(c)
Indicative Content
an explanation which
may include some of
the following points:
properties of nuclear
waste
radioactivity is
dangerous
some isotopes in
nuclear waste have
long
half-lives/radioactive
for thousands of
years
products of fission
are warm
identified radiation
from nuclear waste
e.g alpha, beta,
gamma problems
caused by nuclear
waste
leakage of
radioactivity
contamination of
ground/sea
water/lakes /rivers
contamination of
crops/fish/animals/dri
nking water
harm to
humans/cancer/radia
tion poisoning/
damage to
cells/mutation of
cells or DNA
difficulty in
transporting safely/
stolen by terrorists
fears of local people
solutions for dealing
with nuclear waste
safely
long term storage,
underground /under
the sea
radiation shielding,
lead/steel/concrete/
containers, sealed in
glass.
human safety,
radiation suits, using
tongs/lead jackets
Total marks for question = 12
Mark
(6)
Level
1
0
1-2
safe location, away
from people/remote
areas/sea cooling,
ponds
information to
persuade local
people of safety
No rewardable content
 a limited explanation mentioning at
least one point, but without linking, e.g.
radioactivity is dangerous ; nuclear waste
should be stored underground ; terrorists
might steal nuclear waste;
 the answer communicates ideas using
simple language and uses limited scientific
terminology
 spelling, punctuation and grammar are
used with limited accuracy
2
3-4
 a simple explanation mentioning two
points with an appropriate linkage e.g.
nuclear waste is dangerous and it must be
stored underground ; the isotopes in nuclear
waste have long half-lives so they must be
stored for a long time;
 the answer communicates ideas
showing some evidence of clarity and
organisation and uses scientific terminology
appropriately
 spelling, punctuation and grammar are
used with some accuracy
3
5-6
 a detailed explanation mentioning a
range of points with appropriate linkages
e.g. gamma rays from nuclear waste causes
damage to cells so it must be stored away
from where people live ; the isotopes in
nuclear waste have long half-lives so they
must be stored underground or in remote
areas;
 the answer communicates ideas clearly
and coherently uses a range of scientific
terminology accurately
 spelling, punctuation and grammar are
used with few errors
Q2.
Question
Number
QWC
*
Indicative content
Mark
An explanation
linking some of the
following points
Risks• fuel rods
have high
temperature when
removed from
reactor • different
types of ionising
radiation produce
different dangers
• energy from the
ionising radiation can
be absorbed by the
human body
• (prolonged)
exposure to radiation
can cause tissue /
cell damage and
mutation / damage to
DNA • increased
risk due to long term
exposure to raised
background levels of
radiation • damage
to rods during
transport • leak
from reactor / rods /
reprocessing unit
Safety
precautions• appro
priate working
practices should be
adopted –
protective clothing
and handling
systems should be
used • people
working with
radioactive material
should minimise their
exposure to the
ionising radiation
• intensity of
radiation decreases
with distance from
the source
• personal radiation
dose should be
monitored
• monitoring of
background levels of
radiation • use of
canister to carry fuel
rods
(6)
Level
1
0
1-2
2
3-4
3
5-6
No rewardable material
• a limited explanation of risk or precautions
e.g. alpha particles can cause cancer • the
answer communicates ideas using simple
language and uses limited scientific
terminology • spelling, punctuation and
grammar are used with limited accuracy
• some explanation of risk and precaution
e.g. idea of relative dangers of some ionising
radiations and some sensible suggestions
regarding working practice • the answer
communicates ideas showing some
evidence of clarity and organisation and
uses scientific terminology appropriately
• spelling, punctuation and grammar are
used with some accuracy
• a detailed explanation of appropriate
precautions clearly linked to risks (ORA) e.g.
idea that intensity of radiation decreases
according to the nature of the medium
through which it is travelling therefore the
canister should be of a high density material
in order to reduce escape of ionising
radiation • the answer communicates ideas
clearly and coherently uses a range of
scientific terminology accurately • spelling,
punctuation and grammar are used with few
errors
Q3.
Answer
(a) (i)
(a) (ii)
(a) (iii)
A alpha particles
A suggestion to
include Absorbs
(ionising) radiation
(from the sources)
One from
Buildings/building
materials,
food, plants, water,
outer space,
rocks, air, Sun
Acceptable
answers
Mark
(1)
Stops/reduces
radiation/
radioactivity
(reaching people);
Stops/reduces
(alpha) particles or
any named ionising
radiation (reaching
people); Protects
people/keeps it safe;
Ignore – "so the
source cannot pass
through"
Cosmic rays/waves;
radon (gas);
radioactive waste;
nuclear
accidents/Chernobyl/
nuclear explosions;
nuclear power
stations; do NOT
accept everywhere
ignore alpha, beta,
(1)
(1)
(a) (iv)
Any two relevant
precautions
(b) (i)
Calculation of
number of halflives
8 ÷ 4 = 2 (half lives)
(1) evaluation of
mass
6 ÷ 2 = 3 ÷ 2 = 1.5
(mg) (1)
(b) (ii)
An explanation
linking any two of the
following points
 people inhale
radon (gas) (1)
 radon is quite
likely to/may decay
in the lungs (before
being exhaled) (1)
 causes ionisation
of cells (in lungs) (1)
 increases risk of
(lung) cancer (1)
gamma, microwaves
and X-rays, carbon
dioxide, nitrogen,
(mobile) phones
(2)
Distance (between
students and
source); no touching;
no eating; short
exposure time;(use
of) film badge/
detector ;
Protective clothing;
Use of lead (lined)
box /keep box shut/
sources in box (when
not in use);
(stand behind/use of)
a screen;
Do not point (source)
at students;
Show video/dvd of
demo; Ignore
goggles, gloves, lab
coats,; Answers
referring to the safety
of teacher can score
a maximum of one of
the 2 marks eg use
of tongs
(2)
Award 1 mark for
clearly calculating
mass halves after 4
days
eg 6/2 = 3 (mg) 6/4
= 1.5 scores 2 marks
Allow rounded 2 mg
if clear they
calculated 1.5 mg
give full marks for
correct numerical
answer, 1.5 (mg)
even if no working
Breathe in radon
(gas)/ breathe it in/
radon (gas) gets into
the body; Gives out
radiation in the body
/ alpha (particles)
very ionising;
(2)
causes damage to
(DNA of) cells (in
lung)/cell
mutations/kills cells;
(Damages the body
is insufficient)
(causes lung)
cancer