Q1.

Americium-241 is an isotope of americium.

(a) Which of the isotopes given in the table below is not an isotope of americium?

Isotope Mass number Atomic number

A 243 95

B 243 94

C 242 95

Isotope _____________________

Give a reason for your answer.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)

The graph below shows how the number of americium-241 nuclei in a sample changes
with time.

(b) How many years does it take for the number of americium-241 nuclei to decrease
from 10 000 to 5000?

Time = _______________________ years

Page 1 of 78
 (1)

(c) What is the half-life of americium-241?

Half-life = _______________________ years

(1)
(Total 4 marks)

Q2.
The diagram shows a lithium atom.

(a) What is the mass number of this lithium atom?

Tick one box.

3 4 7 10

(1)

(b) What is the atomic number of a lithium atom?

Tick one box.

3 4 7 10

Give a reason for your answer.

___________________________________________________________________

___________________________________________________________________
(2)

(c) Complete the sentence.

Page 2 of 78
 Choose the answer from the box.

circles levels rings

The electrons in an atom orbit in different energy ____________________ .

(1)

(d) Some atomic nuclei are unstable and decay by emitting an alpha particle or a beta
particle.

Complete the symbols for an alpha particle and a beta particle.

Use answers from the box.

–1 0 1 2 4

(3)

(e) Doctors may use nuclear radiation to diagnose certain types of illness.

The table below gives data about three radiation sources used.

Each source emits beta radiation.

Radiation source Half-life in minutes

Carbon-11 20

Nitrogen-13 10

Oxygen-15 2

Explain why oxygen-15 is likely to pose the least risk to a patient.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)
(Total 9 marks)

Page 3 of 78
Q3.
In the early 20th century, scientists developed an alpha particle scattering experiment
using gold foil.

The diagram shows the paths of some of the alpha particles in the alpha particle
scattering experiment.

(a) Explain how the paths of the alpha particles were used to develop the nuclear model
of the atom.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(4)

(b) Niels Bohr adapted the nuclear model by suggesting electrons orbited the nucleus
at specific distances.

Explain how the distance at which an electron orbits the nucleus may be changed.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Page 4 of 78
 (3)
(Total 7 marks)

Q4.
Scientists sometimes replace one scientific model with a different model.

For example, in the early 20th Century the plum pudding model of the atom was replaced
by the nuclear model of the atom.

Explain what led to the plum pudding model of the atom being replaced by the nuclear
model of the atom.

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________
(Total 6 marks)

Q5.
A student models the random nature of radioactive decay using 100 dice.

He rolls the dice and removes any that land with the number 6 facing upwards.

He rolls the remaining dice again.

The student repeats this process a number of times.

The table below shows his results.

Number of dice
Roll number
remaining

0 100

1 84

2 70

3 59

4 46

Page 5 of 78
 5 40

6 32

7 27

8 23

(a) Give two reasons why this is a good model for the random nature of radioactive
decay.

1. _________________________________________________________________

___________________________________________________________________

2. _________________________________________________________________

___________________________________________________________________
(2)

(b) The student’s results are shown in Figure 1.

Figure 1

Use Figure 1 to determine the half-life for these dice using this model.

Show on Figure 1 how you work out your answer.

Half-life = ________________________ rolls

(2)

Page 6 of 78
(c) A teacher uses a protactinium (Pa) generator to produce a sample of radioactive
material that has a half-life of 70 seconds.

In the first stage in the protactinium generator, uranium (U) decays into thorium (Th)
and alpha (α) radiation is emitted.

The decay can be represented by the equation shown in Figure 2.

Figure 2

Determine the atomic number of thorium (Th) 234.

Atomic number = ______________________

(1)

(d) When protactinium decays, a new element is formed and radiation is emitted.

The decay can be represented by the equation shown in Figure 3.

Figure 3

When protactinium decays, a new element, X, is formed.

Use information from Figure 2 and Figure 3 to determine the name of element X.

___________________________________________________________________
(1)

(e) Determine the type of radiation emitted as protactinium decays into a new element.

Give a reason for your answer.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)

(f) The teacher wears polythene gloves as a safety precaution when handling
radioactive materials.

The polythene gloves do not stop the teacher’s hands from being irradiated.

Explain why the teacher wears polythene gloves.

___________________________________________________________________

___________________________________________________________________

Page 7 of 78
 ___________________________________________________________________

___________________________________________________________________
(2)
(Total 10 marks)

Q6.
Atoms are different sizes.

One of the heaviest naturally occurring stable elements is lead.

Two of its isotopes are lead-206 ( ) and lead-208 ( ).

(a) (i) What is meant by ‘isotopes’?

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________
(2)

(ii) How many protons are in the nucleus of a atom?

__________________
(1)

(iii) How many neutrons are in the nucleus of a atom?

__________________
(1)

(b) A nucleus can be accelerated in a particle accelerator and directed at a large

nucleus. This produces a heavy nucleus that will decay after a short time.

This is shown in Figure 1.

(i) In 1984, nuclei of iron (Fe) were directed at nuclei of lead (Pb). This produced

Page 8 of 78
 nuclei of hassium (Hs).

Complete the equation for this reaction by writing numbers in the empty
boxes.

(3)

(ii) Use the correct answer from the box to complete the sentence.

an electron a proton a neutron

The particle X in part (b)(i) is _________________________________ .

(1)

(iii) After acceleration the iron nuclei travel at a steady speed of one-tenth of the
speed of light.

The speed of light is 3.00 × 108 m/s.

Calculate the time taken for the iron nuclei to travel a distance of 12 000 m.

______________________________________________________________

______________________________________________________________

Time taken = ____________________ s

(2)

(iv) Linear accelerators, in which particles are accelerated in a straight line, are
not used for these experiments. Circular particle accelerators are used.

Suggest why.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________
(3)

(c) Hassium-265 ( ) decays by alpha emission with a half-life of 0.002 seconds.

(i) What is meant by ‘half-life’?

Tick ( ) two boxes.

Page 9 of 78
 Tick ( )

The average time for the number of nuclei to halve

The time for count rate to be equal to background

count

The time for background count to halve

The time for count rate to halve

(2)

(ii) Complete the equation for the decay of Hs-265 by writing numbers in the
empty boxes.

(2)

(d) The table below shows how the atomic radius of some atoms varies with atomic
number.

Atomic Atomic radius in

number picometres (pm)

15 100

35 115

50 130

70 150

95 170

1 pm = 10–12 m

(i) On Figure 2, use the data from the table above to plot a graph of atomic
radius against atomic number and draw a line of best fit.

Two points have been plotted for you.

Figure 2

Page 10 of 78
 (2)

(ii) Scientists believe that the element with atomic number 126 can be produced
and that it will be stable.

Use your graph in Figure 2 to predict the atomic radius of an atom with atomic
number 126.

Atomic radius = ____________________ pm

(1)
(Total 20 marks)

Q7.
(a) Over 100 years ago, scientists thought the atom was like a ‘plum pudding’.
The diagram below shows the plum pudding model of the atom.

Page 11 of 78
 The scientists knew that an atom has negatively charged particles. They also knew
that an atom has no overall charge.

What did the scientists conclude about the charge on the ‘pudding part’ of the
atom?

___________________________________________________________________

___________________________________________________________________
(1)

(b) Two scientists named Rutherford and Marsden devised an experiment to investigate
the plum pudding model of the atom. The experiment involved firing alpha particles
at a thin sheet of gold. The scientists measured how many of the alpha particles
were scattered.

Using the plum pudding model, the scientists predicted that only a few of the alpha
particles would be scattered by more than 4°.

Over several months, more than 100 000 measurements were made.

(i) The results from this experiment caused the plum pudding model to be
replaced by a new model of the atom.

Explain why.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________
(2)

(ii) Suggest one reason why other scientists thought this experiment provided
valid evidence for a new model of the atom.

______________________________________________________________

______________________________________________________________

______________________________________________________________
(1)

Page 12 of 78
 (c) In this question you will be assessed on using good English, organising
information clearly and using specialist terms where appropriate.

Describe the model now used for the structure of an atom.

In your answer you should:

• give details of the individual particles that make up an atom
• include the relative masses and relative charges of these particles.

Do not include a diagram in your answer.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(6)
(Total 10 marks)

Q8.
Atoms contain three types of particle.

(a) Draw a ring around the correct answer to complete the sentence.

electrons and neutrons.

The particles in the nucleus of the atom are electrons and protons.

neutrons and protons.

(1)

(b) Complete the table to show the relative charges of the atomic particles.

Particle Relative charge

Electron –1

Neutron

Proton

Page 13 of 78
 (2)

(c) (i) A neutral atom has no overall charge.

Explain this in terms of its particles.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________
(2)

(ii) Complete the sentence.

An atom that loses an electron is called an _____________________

and has an overall _________________________ charge.

(2)
(Total 7 marks)

Q9.
(a) The figure below shows a helium atom.

(i) Which one of the particles in the atom is not charged?

Draw a ring around the correct answer.

electron neutron proton

(1)

(ii) Which two types of particle in the atom have the same mass?

__________________________ and __________________________

(1)

(iii) What is the atomic number of a helium atom?

Draw a ring around the correct answer.

Page 14 of 78
 2 4 6

Give a reason for your answer.

______________________________________________________________

______________________________________________________________
(2)

(b) Alpha particles are one type of nuclear radiation.

(i) Name one other type of nuclear radiation.

______________________________________________________________
(1)

(ii) Use the correct answer from the box to complete the sentence.

electrons neutrons protons

The difference between an alpha particle and a helium atom is that the alpha

particle does not have any _________________________ .

(1)

(iii) Which one of the following is a property of alpha particles?

Tick (✓) one box.

Have a long range in air

Are highly ionising

Will pass through metals

(1)

(c) Doctors may use nuclear radiation to treat certain types of illness.

Treating an illness with radiation may also harm a patient.

(i) Complete the following sentence.

The risk from treating a patient with radiation is that the radiation may

_________________________ healthy body cells.

(1)

(ii) Draw a ring around the correct answer to complete the sentence.

Radiation may be used to treat a patient if the risk from the

radiation is much bigger than the possible benefit of having

Page 15 of 78
 about the same as

much smaller than

the treatment.
(1)
(Total 9 marks)

Q10.
The diagram shows the structure of an atom.

Not drawn to scale

(a) In 1931 scientists thought that atoms contained only protons and electrons.

Suggest what happened in 1932 to change the idea that atoms contained only
protons and electrons.

___________________________________________________________________

___________________________________________________________________
(1)

(b) The table gives information about the particles in an atom.

Complete the table by adding the names of the particles.

Particle Relative Mass Relative Charge

1 0

very small –1

1 +1
(2)
(Total 3 marks)

Q11.
There are many different isotopes of gold. The isotope, gold-198, is radioactive.
An atom of gold-198 decays by emitting a beta particle.

(a) Complete the following sentences.

Page 16 of 78
 All atoms of gold have the same number of ________________________________

and the same number of __________________________________ .

The atoms from different isotopes of gold have different numbers of ____________ .

A beta particle is an __________________________________ emitted

from the __________________________________ of an atom.

(3)

(b) The graph shows how the count rate from a sample of gold-198 changes with time.

Time in days

Use the graph to calculate the half-life of gold-198.

Show clearly on the graph how you obtain your answer.

___________________________________________________________________

___________________________________________________________________

Half-life = ________________ days

(2)

(c) The diagram shows a map of a river and the river estuary.

Environmental scientists have found that water flowing into one part of the river
estuary is polluted. To find where the pollution is coming from, the scientists use a
radioactive isotope, gold-198.

Page 17 of 78
 The gold-198 is used to find where the pollution is coming from.

Explain how.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)
(Total 7 marks)

Q12.
The diagram represents an atom of beryllium. The three types of particle that make up the
atom have been labelled.

(a) Use the labels from the diagram to complete the following statements.

Each label should be used once.

The particle with a positive charge is ____________________________________ .

The particle with the smallest mass is ___________________________________ .

The particle with no charge is __________________________________________ .

(2)

Page 18 of 78
 (b) What is the mass number of a beryllium atom?

Draw a ring around your answer.

4 5 9 13

Give a reason for your answer.

___________________________________________________________________

___________________________________________________________________
(2)
(Total 4 marks)

Q13.
In the early part of the 20th century, scientists used the ‘plum pudding’ model to explain
the structure of the atom.

Following work by Rutherford and Marsden, a new model of the atom, called the ‘nuclear’
model, was suggested.

Describe the differences between the two models of the atom.

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

Page 19 of 78
 _______________________________________________________________________
(Total 4 marks)

Q14.
(a) The chart gives the number of protons and neutrons within the nuclei of 7 different
atoms, A – G.

Which of these atoms are isotopes of the same element?

___________________________________________________________________

Give a reason for your answer.

___________________________________________________________________

___________________________________________________________________
(2)

(b) Radium-226 is a radioactive isotope that decays into radon gas by emitting alpha
particles.

The decay can be represented by the equation below.

(i) Complete the equation by writing the correct number in each of the boxes.
(2)

(ii) A sample of radium-226 has a count rate of 400 counts per second.
The half-life of radium-226 is 1600 years.

How long will it be before the count rate has fallen to 50 counts per second?

Page 20 of 78
 Show clearly how you work out your answer.

______________________________________________________________

______________________________________________________________

______________________________________________________________

Length of time = _______________ years

(2)

(c) In 1927, a group of women who had been employed to paint watch faces with a
luminous paint sued their former employer over the illnesses caused by the paint.
The women had been told that the paint, which contained radium, was harmless.

The company owners and the scientists working for the company knew that radium
was harmful and took precautions to protect themselves from the radiation. The
women were given no protection.

What important issue did the treatment of the women by the company owners and
scientists raise?

Draw a ring around your answer.

economic environmental ethical social

Give a reason for your answer.

___________________________________________________________________

___________________________________________________________________
(2)

(d) In the 1920s, many people, including doctors, thought that radium could be used as
a treatment for a wide range of illnesses. Medical records that suggested radium
could be harmful were generally ignored. When some of the women who had used
the luminous paint died, their deaths were not blamed on radium.

Suggest a reason why the evidence suggesting that radium was harmful was
generally ignored.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(1)
(Total 9 marks)

Q15.
The ‘plum pudding’ model of the atom was used by scientists in the early part of the 20th
century to explain atomic structure.

Page 21 of 78
(a) Those scientists knew that atoms contained electrons and that the electrons had a
negative charge. They also knew that an atom was electrically neutral overall.

What did this allow the scientists to deduce about the ‘pudding’ part of the atom?

___________________________________________________________________

___________________________________________________________________
(1)

(b) An experiment, designed to investigate the ‘plum pudding’ model, involved firing
alpha particles at a thin gold foil.

If the ‘plum pudding’ model was correct, then most of the alpha particles would go
straight through the gold foil. A few would be deflected, but by less than 4°.

The results of the experiment were unexpected. Although most of the alpha particles
did go straight through the gold foil, about 1 in every 8 000 was deflected by more
than 90°.

Why did this experiment lead to a new model of the atom, called the nuclear model,
replacing the ‘plum pudding’ model?

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(1)

(c) The diagram shows the paths, A, B and C, of three alpha particles. The total number
of alpha particles deflected through each angle is also given.

Page 22 of 78
 (i) Using the nuclear model of the atom, explain the three paths, A, B and C.

A ____________________________________________________________

______________________________________________________________

B ____________________________________________________________

______________________________________________________________

C ____________________________________________________________

______________________________________________________________
(3)

(ii) Using the nuclear model, the scientist E. Rutherford devised an equation to
predict the proportion of alpha particles that would be deflected through
various angles.

The results of the experiment were the same as the predictions made by
Rutherford.

What was the importance of the experimental results and the predictions being
the same?

______________________________________________________________

______________________________________________________________
(1)
(Total 6 marks)

Q16.
The pie chart shows the average proportions of natural background radiation from various
sources in the UK.

Page 23 of 78
(a) (i) Complete the following sentence.

On average, _____________________________ of the natural background

radiation in the UK comes from radon gas.
(1)

(ii) Radon gas is found inside homes.

The table shows the results from measuring the level of radon gas inside four
homes in one area of the UK.

Level of radon gas in

Home
Bq per m3 of air

1 25

2 75

3 210

4 46

Mean 89

One of the homes has a much higher level of radon gas than the other three
homes.

What should be done to give a more reliable mean for the homes in this area
of the UK?

Put a tick ( ) in the box next to your answer.

ignore the data for home number 3

Page 24 of 78
 measure the radon gas level in more homes in this area

include data for homes from different areas of the UK

(1)

(b) Each atom of radon has 86 protons and 136 neutrons.

(i) How many electrons does each atom of radon have?

Draw a ring around your answer.

50 86 136 222
(1)

(ii) How many particles are there in the nucleus of a radon atom?

Draw a ring around your answer.

50 86 136 222
(1)
(Total 4 marks)

Q17.
(a) Atoms of the isotope bismuth-212 decay by emitting either an alpha particle or a
beta particle.
The equation represents what happens when an atom of bismuth-212 decays by
beta emission into an atom of polonium-212.

(i) The bismuth atom and the polonium atom have the same mass number (212).

What is the mass number of an atom?

______________________________________________________________
(1)

(ii) Beta decay does not cause the mass number of an atom to change.

Explain why not.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

Page 25 of 78
 (2)

(b) When an atom of bismuth-212 emits an alpha particle, the atom decays into an
atom of thallium.

An alpha particle is the same as a helium nucleus.

The symbol below represents an alpha particle.

(i) The equation below represents the alpha decay of bismuth-212.

Complete the equation by writing the correct number in each of the two boxes.

(2)

(ii) It is impossible for the alpha decay of bismuth-212 to produce the same
element as the beta decay of bismuth-212.

Explain why.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________
(2)
(Total 7 marks)

Q18.
The names of three different processes are given in List A.
Where these processes happen is given in List B.

Draw a line to link each process in List A to where the process happens in List B.

Draw only three lines.

List A List B

Process Where it happens

in a star

fusion

Page 26 of 78
 in a nuclear reactor

chain reaction

in a smoke precipitator

alpha decay

in the nucleus of an atom

(Total 3 marks)

Q19.
The diagrams show two different models of an atom.

‘Plum pudding’ model Model used today

(a) The particles labelled ‘Xߣ in the plum pudding model are also included in the model
of the atom used today.

What are the particles labelled ‘X’ ?

_________________________
(1)

(b) Scientists decided that the ‘plum pudding’ model was wrong and needed replacing.

Which one of the following statements gives a reason for deciding that a scientific
model needs replacing?

Tick ( ) one box.

Page 27 of 78
 The model is too simple.

The model has been used by scientists for a long time.

The model cannot explain the results from a new experiment.

(1)

(c) The table gives information about the three types of particle that are in the model of
the atom used today.

Particle Relative mass Relative charge

1 +1

very small –1

1 0

Complete the table by adding the names of the particles.

(2)
(Total 4 marks)

Q20.
(a) Background radiation is all around us all the time.

(i) Radon is a natural source of background radiation.

Name another natural source of background radiation.

______________________________________________________________
(1)

(ii) X-rays are an artificial source of background radiation.

Name another artificial source of background radiation.

______________________________________________________________
(1)

(iii) An atom of radon-222 decays by emitting an alpha particle.

The equation representing the decay is shown below.

Page 28 of 78
 How can you tell from the equation that ‘X’ is not an atom of radon?

______________________________________________________________

______________________________________________________________
(1)

(b) Having an X-ray taken increases your exposure to radiation.

The table gives:

• the radiation doses received for 6 different medical X-rays;

• the number of days’ of exposure to natural background radiation each dose is

equivalent to.

Medical X-ray Radiation dose Equivalent number of days

received of exposure to natural
(in arbitrary units) background radiation

Chest 2 2.4

Skull 7 8.4

Pelvis 22 26.4

Hip 44 52.8

Spine 140

CT head scan 200 240

A hospital patient has an X-ray of the spine taken.

Calculate the number of days of exposure to natural background radiation that an X-
ray of the spine is equivalent to.

Show how you work out your answer.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Equivalent number of days = _________________________

(2)

(c) Scientists have shown that X-rays increase the risk of developing cancer.
The scientists came to this conclusion by studying the medical history of people

Page 29 of 78
placed in one of two groups, A or B.
The group into which people were put depended on their X-ray record.

(i) Person J has been placed into group A.

Place each of the people, K, L, M, N and O, into the appropriate group, A or
B.

Person J K L M N O

Medical 3 arm None None 2 skull None 4 leg

X-ray
record

Group A Group B

(1)

(ii) To be able to make a fair comparison, what is important about the number of
people in each of the two groups studied by the scientists?

______________________________________________________________

______________________________________________________________
(1)

(iii) What data would the scientists have compared in order to come to the
conclusion that X-rays increase the risk of developing cancer?

______________________________________________________________

______________________________________________________________
(1)

(iv) The chance of developing cancer due to a CT head scan is about 1 in 10 000.

The chance of developing cancer naturally is about 1 in 4.

Page 30 of 78
 A hospital patient is advised by a doctor that she needs to have a CT head
scan.
The doctor explains to the patient the risks involved.

Do you think that the patient should give her permission for the CT scan to be
taken?

Draw a ring around your answer.

Yes No

Give a reason for your answer.

______________________________________________________________

______________________________________________________________
(1)
(Total 9 marks)

Q21.
(a) The diagram represents a helium atom.

(i) Which part of the atom, K, L, M or N, is an electron?

Part
(1)

(ii) Which part of the atom, K, L, M or N, is the same as an alpha particle?

Part
(1)

(b) A radioactive source emits alpha particles.

What might this source be used for?

Put a tick ( ) in the box next to your answer.

Page 31 of 78
 to monitor the thickness of aluminium foil as it is made in a factory

to make a smoke detector work

to inject into a person as a medical tracer

(1)

(c) The graph shows how the count rate from a source of alpha radiation changes with
time.

What is the count rate after 4 hours?

_______________________ counts per second

(1)
(Total 4 marks)

Q22.
The diagram represents an atom of beryllium. The three types of particle that make up the
atom have been labelled.

Page 32 of 78
(a) Use the labels from the diagram to complete the following statements.

Each label should be used once.

The particle with a positive charge is ____________________________________

The particle with the smallest mass is ___________________________________

The particle with no charge is __________________________________________

(2)

(b) What is the atomic number of a beryllium atom?

Draw a ring around your answer.

4 5 9 13

Give a reason for your answer.

___________________________________________________________________

___________________________________________________________________
(2)

(c) Which one of the following statements describes what can happen to an atom to
change it into an ion?

Tick ( ) one box.

The atom loses a neutron.

The atom loses an electron.

Page 33 of 78
 The atom loses a proton.

(1)
(Total 5 marks)

Q23.
The diagram represents an atom of beryllium.

(a) Complete the following statements by writing one of the letters, J, K or L, in each
box.

Each letter should be used only once.

The particle with a positive charge is

The particle with the smallest mass is

The particle with no charge is

(2)

(b) Give the reason why all atoms have a total charge of zero.

___________________________________________________________________

___________________________________________________________________
(1)

(c) Complete the following sentence.

There are several isotopes of beryllium. Atoms of different beryllium

Page 34 of 78
 isotopes will have different numbers of ___________________________________
(1)

(d) What happens to the structure of an atom to change it into an ion?

___________________________________________________________________

___________________________________________________________________
(1)
(Total 5 marks)

Q24.
The diagram represents an atom of lithium.

(a) (i) Complete the following table of information for an atom of lithium.

Number of protons

Number of electrons

Number of neutrons

(2)

(ii) What is the mass number of a lithium atom?

Draw a ring around your answer.

3 4 7 10

Give a reason for your answer.

______________________________________________________________

______________________________________________________________
(2)

(b) Complete the following sentence by drawing a ring around the correct line in the
box.

Page 35 of 78
 an ion

An atom that has lost an electron is called an isotope

a positive atom
(1)

(c) When an alpha particle is emitted from the nucleus of a radon atom, the radon
changes into polonium.

An alpha particle consists of 2 protons and 2 neutrons.

(i) Complete the following sentence by drawing a ring around the correct line in
the box.

greater than

The mass of a polonium atom is the same as the mass of a radon atom.

smaller than
(1)

(ii) Give a reason for your answer to part (c)(i).

______________________________________________________________

______________________________________________________________
(1)
(Total 7 marks)

Q25.
(a) The diagram represents 3 atoms, K, L and M.

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

Page 36 of 78
 __________ 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.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(3)
(Total 8 marks)

Page 37 of 78
Q26.
Most elements have some isotopes which are radioactive.

(a) What is meant by the terms:

(i) isotopes

______________________________________________________________

______________________________________________________________
(1)

(ii) radioactive?

______________________________________________________________

______________________________________________________________
(1)

(b) The graph shows how the number of nuclei in a sample of the radioactive isotope
plutonium-238 changes with time.

Use the graph to find the half-life of plutonium-238.

Show clearly on the graph how you obtain your answer.

Half-life = ______________ years

(2)

(c) The Cassini spacecraft launched in 1997 took seven years to reach Saturn.

Page 38 of 78
 The electricity to power the instruments on board the spacecraft is generated using
the heat produced from the decay of plutonium-238.

(i) Plutonium-238 decays by emitting alpha particles.

What is an alpha particle?

______________________________________________________________
(1)

(ii) During the 11 years that Cassini will orbit Saturn, the output from the
generators will decrease.

Explain why.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________
(2)

(d) Plutonium-238 is highly dangerous. A tiny amount taken into the body is enough to
kill a human.

(i) Plutonium-238 is unlikely to cause any harm if it is outside the body but is
likely to kill if it is inside the body.

Explain why.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________
(2)

(ii) In 1964, a satellite powered by plutonium-238 was destroyed, causing the

release of radioactive material into the atmosphere.

Suggest why some environmental groups protested about the launch of

Cassini.

______________________________________________________________

______________________________________________________________
(1)
(Total 10 marks)

Q27.
(a) Complete the following table for an atom of uranium-238 ( )

Page 39 of 78
 mass number 238

number of protons 92

number of neutrons
(1)

(b) Complete the following sentence.

The name given to the number of protons in an atom is the proton number or the

______________________________ .
(1)

(c) An atom of uranium-238 ( ) decays to form an atom of thorium-234 ( ).

(i) What type of radiation, alpha, beta or gamma, is emitted by uranium-238?

______________________________________________________________
(1)

(ii) Why does an atom that decays by emitting alpha or beta radiation become an
atom of a different element?

______________________________________________________________

______________________________________________________________
(1)
(Total 4 marks)

Q28.
In the early part of the 20th century, scientists used the ‘plum pudding’ model to explain
the structure of the atom.

Following work by Rutherford and Marsden, a new model of the atom, called the ‘nuclear’
model, was suggested.

Page 40 of 78
 (a) Describe the differences between the two models of the atom.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(4)

(b) In their investigation, Rutherford and Marsden fired positively charged alpha
particles at a very thin sheet of gold. Over a period of several months, the scientists
made over 100 000 measurements. These measurements showed that:

• a very small number of alpha particles were deflected backwards from the gold
foil.

Use the nuclear model to explain this experimental result.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)

(c) Why did the work of Rutherford and Marsden convince many scientists that the
‘plum pudding’ model of the atom was incorrect?

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)
(Total 8 marks)

Q29.
The diagram shows a helium atom.

Page 41 of 78
(a) (i) Use the words in the box to label the diagram.

electron neutron proton

(2)

(ii) An alpha particle is the same as the nucleus of a helium atom.

How is an alpha particle different from a helium atom?

______________________________________________________________

______________________________________________________________
(1)

(b) The graph shows how the count rate from a sample of radioactive sodium-24
changes with time.

(i) How many hours does it take for the count rate to fall from 100 counts per
second to 50 counts per second?

Page 42 of 78
 Time = _______________ hours
(1)

(ii) What is the half-life of sodium-24?

Half-life = _______________ hours

(1)

(c) A smoke detector contains a small amount of americium-241.

Americium-241 is a radioactive substance which emits alpha particles. It has a half-

life of 432 years.

(i) Which one of the following statements gives a reason why the americium-241
inside the smoke detector will not need replacing?

Put a tick ( ) in the box next to your answer.

The alpha particles have a low energy.

People replace smoke detectors every few

years.

Americium-241 has a long half-life.

(1)

(ii) The diagram shows the label on the back of the smoke detector.

Why do people need to know that the smoke detector contains a radioactive
material?

______________________________________________________________

______________________________________________________________
(1)
(Total 7 marks)

Q30.
(a) The diagram shows the parts of a smoke detector. The radioactive source emits
alpha particles.

Page 43 of 78
 The alpha particles ionise the air inside the sensor which causes a small electric
current. Any smoke getting into the sensor changes the current. The change in
current sets the alarm off.

(i) The smoke detector would not work if a radioactive source that emitted only
gamma rays was used.

Why not?

______________________________________________________________

______________________________________________________________
(1)

(ii) Curium-242 is a radioactive isotope with a half-life of 160 days. It emits alpha
particles.

Why is curium-242 not suitable for use inside smoke detectors?

______________________________________________________________

______________________________________________________________
(1)

(iii) Curium-242 and curium-244 are two of the isotopes of the element curium.

How is an atom of curium-242 different from an atom of curium-244?

______________________________________________________________

______________________________________________________________
(1)

(b) Sections of steel are often joined by welding them together. The diagram shows how
a radioactive source can be used to check for tiny cracks in the weld.

Page 44 of 78
 Cracks in the weld will be shown up on the photographic film below the thick steel
plate.

(i) Which type of source, alpha, beta or gamma, should be used to check the
weld?

______________________________________________________________
(1)

(ii) Give a reason why the other two types of source cannot be used.

______________________________________________________________

______________________________________________________________
(1)

(c) The diagram shows a map of a river and its estuary.

Environmental scientists have found that the water flowing into one part of the river
estuary is polluted. To find where the pollution is coming from, the scientists use a
radioactive isotope, gold-198.

(i) Explain how the gold-198 is used to find where the pollution is coming from.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________
(2)

Page 45 of 78
 (ii) The graph shows how the count rate from a sample of gold-198 changes with
time.

Use the graph to calculate the half-life of gold-198.

Show clearly on the graph how you obtain your answer.

______________________________________________________________

______________________________________________________________

Half-life = _______________ days

(2)
(Total 9 marks)

Q31.
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

Page 46 of 78
 charge.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(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?

______________________________________________________________

______________________________________________________________
(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?

______________________________________________________________
(1)

(iii) The nucleus of an atom splits into smaller parts in a reactor.

What name is given to this process?

______________________________________________________________
(1)
(Total 7 marks)

Q32.
A radioactive source emits alpha (α), beta (β) and gamma (γ) radiation. The diagram
shows what happens to the radiation as it passes between two charged metal plates.

Page 47 of 78
(a) Which line P, Q or R shows the path taken by:

(i) alpha radiation __________

(1)

(ii) gamma radiation? __________

(1)

(b) The diagram shows three different boxes and three radioactive sources. Each
source emits only one type of radiation and is stored in a different box. The box
reduces the amount of radiation getting into the air.

Draw three lines to show which source should be stored in which box so that the
minimum amount of radiation gets into the air.
(2)

(c) The graphs show how the count rates from three different radioactive sources, J, K,
and L, change with time.

Page 48 of 78
 (i) Which source, J, K, or L, has the highest count rate after 24 hours?

_______
(1)

(ii) For source L, what is the count rate after 5 hours?

_______________ counts per second

(1)

(iii) Which source, J, K, or L, has the longest half-life?

____________________
(1)

(iv) A radioactive source has a half-life of 6 hours.

What might this source be used for?

Put a tick ( ) in the box next to your choice.

To monitor the thickness of paper as it is made in a factory

To inject into a person as a medical tracer

To make a smoke alarm work

(1)
(Total 8 marks)

Q33.
The diagram represents an atom of lithium.

Page 49 of 78
 (i) Complete the diagram by writing in the spaces the name of each type of particle.
Use only words given in the box. Each word may be used once or not at all.

electron neutron nucleus proton

(3)

(ii) Which type of particle found inside the atom is uncharged?

___________________________________________________________________
(1)

(iii) What is the mass number of this atom, 3, 4, 7 or 10?

___________________________________________________________________

Give a reason for your choice.

___________________________________________________________________

___________________________________________________________________
(2)
(Total 6 marks)

Q34.
(a) The diagrams represent three atoms X, Y and Z.

Page 50 of 78
 X Y Z

Which two of the atoms are from the same element?

___________________________________________________________________

Give a reason for your answer.

___________________________________________________________________

___________________________________________________________________
(2)

(b) In the early part of the 20th century some scientists investigated the paths taken by
positively charged alpha particles into and out of a very thin piece of gold foil. The
diagram shows the paths of three alpha particles.

Explain the different paths A, B and C of the alpha particles.

To gain full marks in this question you should write your ideas in good English. Put
them into a sensible order and use the correct scientific words.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(3)
(Total 5 marks)

Q35.
(a) Uranium-234 (234U) is a radioactive element. The graph shows the number of
protons and neutrons in the nuclei of the elements formed when uranium-234
decays.

Page 51 of 78
 (i) How does the graph show that uranium-234 (234U) and thorium-230 (230Th) emit
alpha particles?

______________________________________________________________
(1)

(ii) What makes uranium and thorium different elements?

______________________________________________________________
(1)

(iii) Radioactive decay may also produce gamma radiation.

Why does the emission of gamma radiation not cause a new element to be
formed?

______________________________________________________________

______________________________________________________________
(1)

(b) The graph shows how the thickness of different materials needed to absorb 90% of
the gamma radiation emitted by a source depends on the energy of the radiation.
The energy of the gamma radiation is given in units called electron-volts.

Page 52 of 78
 (i) Which of the materials shown is least effective at absorbing gamma radiation?
Use the information in the graph to give a reason for your answer.

______________________________________________________________

______________________________________________________________
(1)

(ii) For gamma radiation of energy 1.5 million electron-volts, how many times
more effective is steel than water at absorbing the radiation? Show clearly how
you obtain your answer.

______________________________________________________________

______________________________________________________________

______________________________________________________________
(2)

(c) Scientists in the early twentieth century thought that atoms were made up of
electrons scattered inside a ball of positive charge. This was called the ‘plum-
pudding’ model of the atom.

Plum pudding model

Page 53 of 78
Rutherford and Marsden did an experiment, in which a beam of alpha particles was
aimed at a thin sheet of gold.
Explain how the results of this experiment led to a new model of the atom.
You may include one or more diagrams in your answer.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(3)
(Total 9 marks)

Page 54 of 78
Mark schemes

Q1.
(a) B
reason only scores if B is chosen
1

americium has an atomic number of 95

allow proton number for atomic number
allow B has a different atomic number
allow B has an atomic number of 94
1

(b) 430 (years)

allow an answer between 420 and 440 (years)
1

(c) 430 (years)

or
their answer to part (b)
allow an answer between 420 and 440 (years)
1
[4]

Q2.
(a) 7
1

(b) 3
1

number of protons
reason only scores if 3 chosen
1

(c) levels
1

(d)
correct order only
1
1

(e) shorter half-life (than the other sources)

1

exposure time to radiation is shorter

1
[9]

Page 55 of 78
Q3.
(a) most alpha particles pass straight through the atom
1

which shows that the atom is mostly empty space

1

very few alpha particles are deflected through a large angle

1

which shows the atom contains a nucleus where the mass /

charge of the atom is concentrated
1

(b) electron may absorb electromagnetic radiation

full credit may be scored for a description of an electron
emitting electromagnetic radiation
1

(and) move further from the nucleus

1

to a higher energy level

1
[7]

Q4.
Level 3 (5–6 marks):
A detailed and coherent explanation is provided. The student gives examples that argue a
strong case and demonstrate deep knowledge. The student makes logical links between
clearly identified, relevant points.

Level 2 (3–4 marks):

An attempt to link the description of the experiment and the results with differences
between the two models. The student gives examples of where the plum pudding model
does not explain observations. The logic used may not be clear.

Level 1 (1–2 marks):

Simple statements are made that the nuclear model is a better model. The response may
fail to make logical links between the points raised.

0 marks:
No relevant content.

Indicative content
• alpha particle scattering experiment
• alpha particles directed at gold foil
• most alpha particles pass straight through
• (so) most of atom is empty space
• a few alpha particles deflected through large angles
• (so) mass is concentrated at centre of atom
• (and) nucleus is (positively) charged
• plum pudding model has mass spread throughout atom
• plum pudding model has charge spread throughout atom
[6]

Page 56 of 78
Q5.
(a) cannot predict which dice / atom will ‘decay’
accept answers given in terms of ‘roll a 6’
1

cannot predict when a dice / atom will ‘decay’

1

(b) 3.6 to 3.7 (rolls)

allow 1 mark for attempt to read graph when number of dice
= 50
2

(c) 90
1

(d) uranium
1

(e) beta
1

proton number has gone up (as neutron decays to proton and e–)
1

(f) prevents contamination

or

prevents transfer of radioactive material to teacher’s hands

1

which would cause damage / irradiation over a longer time period.

1
[10]

Q6.
(a) (i) (atoms with the) same number of protons
allow same atomic number
or same proton number
1

(atoms with) different number of neutrons

allow different mass number
1

(ii) 82
1

(iii) 124
1

(b) (i)

Page 57 of 78
 1 mark for each correct box
3

(ii) (a) neutron

1

(iii) 4.0 × 10-4 (s)

or
0.0004
3.00 × 108 × 0.1 = 12 000 / t
gains 1 mark
2

(iv) particles need to travel a large distance

1

equipment would have to be very long

1

with circular paths long distances can be accommodated in a smaller

space
1

(c) (i) the average time for the number of nuclei to halve
1

the time for count rate to halve

1

(ii)

1 mark if top boxes total = 265

and bottom boxes total = 108
1 mark for 4 and 2 for alpha
2

(d) (i) 3 plotted points

± ½ small square
1

best line through points

1

(ii) 190−205 (pm)

or correct from student’s line
1

Page 58 of 78
 [20]

Q7.
(a) (an equal amount of) positive charge
do not accept charge on the atom / nucleus is positive
1

(b) (i) a (significant) number of alpha particles were scattered by more than 4°
or
alpha particles deflected backwards
accept (some) measurements / results were unexpected
1

measurements / results could not be explained by ‘plum pudding’ model

or
measurements / results did not support predictions
can be explained by the nuclear model is insufficient
accept measurements / results did not support hypothesis
1

(ii) many / (over)100 000 measurements / results taken

accept Rutherford(and Marsden) were respected scientists
or
scientists were respected
accept measurements / results taken over several months
the experiment was repeated many times is insufficient
1

(c) Marks awarded for this answer will be determined by the Quality of Written
Communication (QWC) as well as the standard of the scientific response.
Examiners should also refer to the information on page 5 and apply a ‘best-fit’
approach to the marking.

0 marks
no relevant content

Level 1 (1−2 marks)

A brief description is given with some particles correctly named

Level 2 (3−4 marks)

A description is given with all three particles named
plus either
the polarity of charge associated with the
three particles
or
the relative mass of the three particles
or
the relative mass for one particle and the relative charge for one particle given

Level 3 (5−6 marks)

A more detailed description is given, naming the particles and polarity of
charge
and either
the relative mass is given for at least two particles
or

Page 59 of 78
 the relative charge is given for at least two particles

Examples of the points made in the response

brief description

contains protons, neutrons and electrons

protons are positive

electrons are negative
neutrons are uncharged

has a nucleus

relative charge

proton +1
electron − 1
neutron 0

relative mass

proton 1
neutron 1
electron (about) 1 / 2000
accept protons and neutrons have the same mass
accept electrons have tiny / negligible mass
zero mass is neutral

more detailed description

protons and neutrons make up the nucleus

electrons orbit the nucleus
electrons are in shells
most of the atom is empty space
nucleus occupies a very small fraction of the volume of the atom
electrons orbit at a relatively large distance from the nucleus
most of the mass of the atom is contained in the nucleus
the nucleus as a whole is positively charged total number of protons in the
nucleus equals the total number of electrons orbiting it in an atom
6
[10]

Q8.
(a) neutrons and protons
1

(b) 0
1

(+)1
1

(c) (i) total positive charge = total negative charge

accept protons and electrons have an equal opposite charge
1

Page 60 of 78
 (because) no of protons = no of electrons
1

(ii) ion
1

positive
1
[7]

Q9.
(a) (i) neutron
1

(ii) neutron
proton
both required, either order
1

(iii) 2
1

number of protons
do not accept number of electrons
1

(b) (i) any one from:

• beta

• gamma
accept correct symbols
accept positron / neutrino / neutron
cosmic rays is insufficient
1

(ii) electrons
1

(iii) are highly ionising

1

(c) (i) mutate / destroy / kill / damage / change / ionise

Harm is insufficient
1

(ii) much smaller than

1
[9]

Q10.
(a) neutron discovered
1

(b) neutron
all 3 in correct order

Page 61 of 78
 electron
allow 1 mark for 1 correct

proton
2
[3]

Q11.
(a) protons, electrons
both required, either order
1

neutrons
1

electron, nucleus
both required, this order
1

(b) 2.7 (days)

allow 1 mark for showing correct use of the graph
2

(c) put source into water at one point on bank

accept the idea of testing different parts of the river bank at
different times
1

see if radiation is detected in polluted area

accept idea of tracing

or

put source into water at three points on bank (1)

see if radiation is detected downstream of factory or farmland or sewage
treatment works (1)
1
[7]

Q12.
(a) proton
all 3 in correct order

electron
allow 1 mark for 1 correct do not

neutron
accept letters p, e, n
2

(b) 9
reason only scores if 9 is chosen
1

Page 62 of 78
 number of neutrons and protons
1
[4]

Q13.
any two pairs from:
to gain credit it must be clear which model is being described
do not accept simple descriptions of the diagram without
comparison

• nuclear model mass is concentrated at the centre / nucleus (1)

accept the nuclear model has a nucleus / the plum pudding
model does not have a nucleus for 1 mark

plum pudding model mass is evenly distributed (1)

• nuclear model positive charge occupies only a small part of the atom (1)

plum pudding model positive charge spread throughout the atom (1)

• nuclear model electrons orbit some distance from the centre (1)
accept electrons in shells / orbits provided a valid
comparison is made with the plum pudding model

plum pudding electrons embedded in the (mass) of positive (charge) (1)

do not accept electrons at edge of plum pudding

• nuclear model the atom mainly empty space (1)

plum pudding model is a ‘solid’ mass (1)

[4]

Q14.
(a) BEG
all 3 required and no other
any order
1

same number of / 88 protons (and different numbers of neutrons)

same number of electrons is insufficient
1

(b) (i) 222

1

86
1

(ii) 4800
allow 1 mark for obtaining 3 half-lives
2

(c) ethical
1

Page 63 of 78
 deceived / lied to (about safety of working conditions)
accept (women) not warned of the dangers
given no protection is insufficient
or
value own / scientists' lives more than women
or
did not treat women humanely
1

(d) accept any sensible suggestion

eg
too many interests in continued use of radium

evidence may cause public unrest

do not accept not enough evidence

doctors not want to be blamed for illnesses (caused by radium)

accept doctors not wanting to be sued (for harm caused by
using radium)

doctors thought (possible) benefits outweighed (possible) risks

do not accept did not know radium could be harmful
believe radium could treat illnesses is insufficient
1
[9]

Q15.
(a) has an equal amount of positive charge
accept pudding/it is positive
1

(b) (experimental) results could not be explained using ‘plum pudding’ model
or
(experimental) results did not support plum pudding model
accept (experimental) results disproved plum pudding model
1

(c) (i) A – most of atom is empty spaceormost of atom concentrated at the centre
1

B – nucleus is positive (so repels alpha particles)

accept nucleus has the same charge as alpha
1

C – nucleus is very small

accept nucleus is positive if not scored for B
or
nucleus is a concentrated mass
accept nucleus has a very concentrated charge
1

(ii) (if predictions correct, this) supports the new model

answers should be in terms of the nuclear model
accept supports his/new/nuclear theory

Page 64 of 78
 accept proves for supports
accept shows predictions/ Rutherford was correct
1
[6]

Q16.
(a) (i) half / 50 %
1

(ii) Measure the radon gas level in more homes in this area
1

(b) (i) 86
1

(ii) 222
1
[4]

Q17.
(a) (i) (total) number of protons plus neutrons
accept number of nucleons
accept amount for number
do not accept number of particles in the nucleus
1

(ii) number of neutrons decreases by one

1

number of protons increases by one

accept for both marks a neutron changes into a proton
1

(b) (i)
1
correct order only
1

(ii) the number of protons determines the element

accept atomic number for number of protons
1

alpha and beta decay produce different changes to the number of protons
there must be a comparison between alpha and beta which
is more than a description of alpha and beta decay alone
or
alpha and beta decay produce different atomic numbers
ignore correct reference to mass number
1
[7]

Q18.

Page 65 of 78
 three lines correct
allow 1 mark for each correct line
if more than 1 line is drawn from a box in List A, mark each
line incorrect

[3]

Q19.
(a) electron(s)
1

(b) 3rd box ticked

The model cannot explain the results from a new experiment

1

(c) all three correct

Particle

Proton

Electron

Neutron

allow 1 mark for 1 correct

2
[4]

Q20.
(a) (i) any one from:

• food / drink

• rocks / building materials

Page 66 of 78
 • cosmic rays / rays from space
accept correctly named example
1

(ii) any one from:

• nuclear power / coal power (stations)

accept nuclear waste

• nuclear accidents
accept named accident eg Chernobyl

• nuclear weapons testing

accept named medical procedure which involves a
radioactive source
accept radiotherapy
nuclear activity / radiation is insufficient
do not accept CT scans
1

(iii) different number of / fewer protons

accept does not have 86 protons
accept only has 84 protons
or
different atomic number
do not accept bottom number different
reference to mass number negates this mark
1

(b) 168
accept 169 if clear, correct method is shown
allow 1 mark for a correct dose ratio involving the spine
eg 2:140 etc
or ratio of days to dose is 1.2
or ratio of dose to days is 0.83
2

(c) (i)
Group A Group
B

JMO KLN

all correct
any order within each group
1

(ii) similar (number) / same (number) / large (number)

accept the same specific number in each group eg three
reference to other factors such as age is neutral
1

(iii) how many people in each group developed cancer

Page 67 of 78
 a clear comparison is required
1

(iv) there are no marks for Yes or No the

mark is for the reason

Yes
the benefit of having the scan is greater than the risk
or
the risk is (very) small (compared to the chance from natural causes)
accept the risk is much greater from natural causes

No
no additional risk is acceptable
1
[9]

Q21.
(a) (i) L
1

(ii) M
1

(b) To make a smoke detector work.

1

(c) 40
no tolerance
1
[4]

Q22.
(a) proton

electron

neutron
all 3 in correct order
allow 1 mark for 1 correct
do not accept letters p, e, n
2

(b) 4
reason only scores if 4 is chosen
1

number of protons
accept number of electrons
accept there are 4 protons and 4 electrons
do not accept there are 4 protons and electrons
1

(c) The atom loses an electron.

Page 68 of 78
 1
[5]

Q23.
(a) L

K
all 3 in correct order
allow 1 mark for 1 correct
2

(b) number of electrons = number of protons

accept amount for number
1

(c) neutrons
this answer only
1

(d) loses / gains electron(s)

1
[5]

Q24.
(a) (i) all correct
accept presented as a tally chart

Number of protons 3

Number of electrons 3

Number of neutrons 4

allow 1 mark for 1 correct

2

(ii) 7
reason may score even if 7 not chosen
1

number of protons and neutrons

accept number of particles in the nucleus
accept number of nucleons
do not accept number of electrons and neutrons
1

(b) an ion
1

(c) (i) smaller than

1

Page 69 of 78
 (ii) radon loses an alpha (particle)
or
radon loses an (alpha) particle
or
(mass of) polonium plus an alpha = (mass) radon
or
radon loses 2 protons and 2 neutrons (to become polonium)
accept radon has less protons and neutrons
1
[7]

Q25.
(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 4

or
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 2

or
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 α for 1 mark
4
2

an alpha particle is a helium nucleus is insufficient for this

mark
1
[8]

Page 70 of 78
Q26.
(a) (i) (atoms / elements with) the same number of protons but different numbers
of neutrons
accept (atoms / elements with) different mass number but
same atomic number
1

(ii) substances that give out radiation

accept alpha, beta or gamma for radiation
accept an unstable nucleus that decays
radioactive decay takes place is insufficient
1

(b) 85 years
± 2 years
allow 1 mark for showing correct method on the graph
2

(c) (i) a helium nucleus

accept 2 neutrons and 2 protons
accept 2 4He
do not accept helium atom
1

(ii) the rate of decay (of plutonium) decreases

accept fewer (plutonium) nuclei (to decay)
accept radioactivity decreases
1

less heat produced

do not accept energy for heat
1

(d) (i) (outside the body)

alpha (particles) cannot penetrate into the body

(inside the body)

1

(heat produced from decay) damages / kills cells / tissues

accept causes cancer for damages / kills cells / tissues
accept highly toxic
1

(ii) any one from:

• worried same could happen again

• an accident may cause radiation to be spread around the Earth /

atmosphere

• idea of soil contamination resulting from accident / release of radioactive

material

Page 71 of 78
 • idea of negative effect on health resulting from accident / release of
radioactive material
accept any sensible suggestion
1
[10]

Q27.
(a) 146
1

(b) atomic number

1

(c) (i) alpha

1

(ii) number of protons changes

accept atomic number changes
accept loses or gains protons
do not accept protons with any other particle e.g. number of
protons and neutrons changes incorrect
do not accept any reference to mass number
1
[4]

Q28.
(a) any two pairs from:

• nuclear model mass is concentrated at the centre / nucleus (1)

plum pudding model mass is evenly distributed (1)

accept the nuclear model has a nucleus/the plum pudding
model does not have a nucleus for 1 mark

• nuclear model positive charge occupies only a small part of the atom (1)

plum pudding model positive charge spread throughout the atom (1)
accept electrons in shells/ orbits provided a valid comparison
is made with the plum pudding model
do not accept on its own
do not accept electrons at edge of plum pudding

• nuclear model electrons orbit some distance from the centre / nucleus (1)

plum pudding electrons embedded in the (mass) of positive (charge) (1)

• nuclear model the atom mainly empty space (1)

plum pudding model is a ‘solid’ mass (1)

to gain credit it must be clear which model is being described
do not accept simple descriptions on the diagram without
comparison
4

Page 72 of 78
 (b) nucleus must be positive to deflect/ repel alpha particles
answers in terms of electrons/negative charge causing
deflection negates mark answers in terms of reflection
negates mark
1

nucleus (very) small so few alpha particles deflected backwards

accept most of atom empty space so most pass through
1

(c) many/ 100 000 measurements taken

accept results for measurements accept data valid / reliable
1

findings could not be explained by plum pudding model

accept a specific finding that could not be explained
eg some alpha particles were deflected backwards
1
[8]

Q29.
(a) (i)

all 3 labels correct

allow 1 mark for 1 correct label
2

(ii) has no electrons

it = alpha
allow alpha has a positive(charge)
allow a helium (atom) has no (charge)
do not accept general properties of alpha
do not accept general answers in terms of size / density /
mass etc
1

(b) (i) 15 (hours)

accept any answer between 14.8 and 15.2 inclusive
1

(ii) 15 (hours) or their (b) (i)

Page 73 of 78
 1

(c) (i) americium-241 has a long half life

1

(ii) any one from:

• alpha (particles) are harmful to …

accept radiation / radioactive material is harmful to …
accept specific example of harm
eg can cause cancer
accept radiation is poisonous if ingested / inhaled
do not accept it is poisonous / in case of leakage

• so they dispose of it safely / appropriately

• so they don’t break it open / open it

accept do not touch the radioactive source

• so they can make a choice about having a radioactive source (in the
house)
it = radioactive material
1
[7]

Q30.
(a) (i) gamma hardly ionises the air
accept does not ionise
accept gamma radiation is not charged
do not accept answers in terms of danger of gamma or other
properties
1

(ii) half-life (too) short

accept need frequent replacement ‘it’ refers to curium-242
1

(iii) (two) fewer neutrons

accept different numbers of neutrons if a number is specified
it must be correct
do not accept more neutrons unless curium-244 is specified
1

(b) (i) gamma

accept correct symbol
1

(ii) both absorbed by the metal / steel / weld

only scores if (b)(i) is correct
accept cannot pass through the metal / steel / weld
1

(c) (i) put source into water at one point on bank

accept the idea of testing different parts of the river bank at
different times

Page 74 of 78
 1

see if radiation is detected in polluted area

accept idea of tracing
1

(ii) 2.7 (days)

allow 1 mark for showing correct use of the graph
2
[9]

Q31.
(a)
Particle Relative Relative
Mass 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

Page 75 of 78
 accept fision
do not accept any spelling that may be taken as fusion
1
[7]

Q32.
(a) (i) P
1

(ii) Q
1

(b) 3 lines correct

allow 1 mark for 1 correct line

two lines drawn from any source or box – both incorrect
2

(c) (i) K
1

(ii) 56
accept 50 – 60 inclusive
1

(iii) K
1

(iv) to inject... tracer

1
[8]

Q33.
(i) each correct label scores 1 mark

Page 76 of 78
 (ii) neutron
1

(iii) 7
1

number of protons and neutrons or number of nucleons or number of

particles in the nucleus
accept number of particles in the
centre only if first answer = 7
1
[6]

Q34.
(a) Y and Z
1

they have the same number of protons or same atomic number

accept they have the same number of electrons or same
number of protons and electrons
allow only different in number of neutrons N.B. independent
marks
1

(b) Quality of written communication

for correct use of terms underlined in B or C
Q Q
1

A – alpha particle passes straight through the empty space of the atom
or it is a long way from the nucleus
describes 3 tracks correctly for 2 marks
describes 2 or 1 track correctly for 1 mark

B – alpha particle deflected / repelled / repulsed by the (positive) nucleus

C – alpha particle heading straight for the nucleus is deflected / repelled /

repulsed backwards
do not accept hits the nucleus
do not accept answers referring to refraction
do not accept answers in terms of reflected backwards
unless qualified in terms of repulsion
mention of difference in charge on nucleus negates that
track
max 2
[5]

Q35.
(a) (i) both lose 2 protons and (2) neutrons
accept changes by 2 protons and 2 neutrons
1

(ii) different number of protons (in the nucleus)

accept different atomic number

Page 77 of 78
 do not accept different number of protons and neutrons or
different mass number
ignore electrons
1

(iii) gamma involves no change in the number of protons (in the nucleus)
or gamma is a wave (not a particle)
do not accept number of neutrons
and / or protons
ignore electrons
1

(b) (i) water because

both material and reason required

for all energy values the thickness

of water needed to absorb (90% of)
the radiation is more than the other materials
accept thickness of water required is always more
than the other materials
1

(ii) 6
allow 1 mark for obtaining both correct values 72
and 12 from graph
allow 1 mark for incorrect values 71 and / or
11 from graph evaluated correctly
2

(c) any three from:

may be scored on annotated diagram provided
not negated elsewhere

• most (alpha) particles passed

undeflected / straight through the gold

• suggesting most of the atom is empty (space)

• a few (alpha) particles scattered / deflected through (very) large angles

accept repelled
do not accept reflected / rebound /
bounce back

• suggesting a concentrated / small nucleus

• nucleus is positive because it repels the positive (alpha) particles

no reference to experiment, maximum 1 mark
3
[9]

Page 78 of 78