Oxford Revise AQA GCSE Combined Science Foundation | Chapter P7 answers

P7: Nuclear radiation

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Mark

AO / Specification reference

01.1

the iodine-131 has decayed into a different element

1

1

AO3

6.4.2.1

6.4.2.2

01.2

it is random

1

AO3

6.4.2.1

01.3

eight days

accept eight days with no working for two marks

accept indication of having drawn on the graph takes eight hours for one mark

2

AO2

6.4.2.3

01.4

below

1

AO3

6.4.2.3

02.1

A

1

AO1

6.4.2.1

02.2

C

1

AO1

6.4.2.1

02.3

α

1

AO1

6.4.2.1

02.4

Becquerel/Bq

do not accept bq or BQ

1

AO1

6.4.2.1

02.5

is the number of decays recorded each second by a detector/Geiger-Muller tube

accept other named type of detector

1

AO1

6.4.2.1

03.1

six hours

1

AO2

6.4.2.3

03.2

250

it is another half-life

1

1

AO2

6.4.2.3

03.3

radioactive decay is a random process

1

AO3

6.4.2.1

03.4

alpha radiation does not go through the human body/alpha radiation is very ionising/harmful to human cells

1

AO2

6.4.2.4

04.1

Type

Range in air

gamma

> 3 m

beta

1 m

alpha

< 10 cm

all correct for two marks

one correct for one mark

2

AO1

4.4.2.1

04.2

no

the radiation that is the most ionising (is alpha)

(which) has the smallest range in air

1

1

1

AO2

4.4.2.1

04.3

the aluminium absorbs alpha and beta radiation (so the activity goes down)

gamma is not stopped by the aluminium (so you can still detect radiation)

1

1

AO2

4.4.2.1

04.4

nitrogen – beta

radon – alpha

barium – gamma

2

AO3

6.4.2.2

05.1

\(
{}_{{\rm{-1}}}^{\rm{0}}{\rm{X}}
\)

1

AO2

6.4.2.2

05.2

beta/β

1

AO2

6.4.2.2

05.3

the time it takes for the activity/mass of a radioactive material to halve

1

AO1

6.4.2.3

05.4

\(
\frac{{{\rm{80}}}}{{\rm{2}}}= 40 \rm{\ counts \ per \ minute}
\)

1

AO2

6.4.2.3

05.5

sodium-24 has a shorter half-life than magnesium-24

1

AO3

6.4.2.3

06.1

contamination — the unwanted presence of radioactive atoms on other materials

irradiation — process of exposing an object to nuclear radiation

2

AO1

6.4.2.4

06.2

An irradiated object does not become radioactive

1

AO1

6.4.2.4

06.3

yes

eating things that have been irradiated does not make you radioactive

1

1

AO3

6.4.2.4

07.1

alpha

1

AO2

4.4.2.2

07.2

beta particle

1

AO2

4.4.2.2

07.3

14

7

1

1

AO2

6.4.2.2

07.4

\({}_{92}^{238}\rm{U} \rightarrow {}_{90}^{234}\rm{Th} + {}_{2}^{4}\rm{He}\)

1

1

AO2

6.4.2.2

08.1

gamma, beta, alpha

1

AO1

6.4.2.1

08.2

damaged/killed

1

AO1

6.4.2.4

08.3

peer review

1

AO1

6.4.2.1

08.4

for example:

put the source next to a Geiger counter

start by putting paper between the source and the counter

if the count rate goes down, the source is emitting alpha radiation

repeat with aluminium

if the count rate goes down, the source is emitting beta radiation

repeat with lead

if the count rate goes down, the source is emitting gamma radiation

6

AO1

6.4.2.1

09.1

thermometer

1

AO1

6.1.2.1

09.2

protect work surface

1

AO3

09.3

time (it takes the water to cool down by a certain amount)

1

AO2

6.1.2.1

09.4

the (independent) variable is categoric/words

1

AO1

6.1.2.1

09.5

polystyrene

1

AO3

6.1.2.1

09.6

repeat experiment/heat water to a set temperature

accept other sensible answers

1

AO3

6.1.2.1

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