CHAPTER 6
NUCLEAR ENERGY
6.1 RADIOACTIVE SUBSTANCES
1. A radioactive substance is a substance that has unstable nucleus.
2. The unstable nucleus breaks up continuously to become stable.
3. The breaking process produces energy and tiny particles known as radiation. This process is
called ‘Radioactive Decay’.
4. The radioactive radiation produced during radioactive decay are the:
a. alpha particles
b. beta particles
c. gamma particles
5. The process of radioactive decay is as in the diagram below:
6. The radioactive radiation is dangerous because it can kill our body cells, causes
cancer and also deformity in unborn babies.
Beta ray
α
β
Gamma ray
γ
Alpha ray
A piece of
paper
Thin
aluminium
Lead
7. The characteristics of the three types of radioactive radiations are:
Alpha particles
1. Consists of helium
nucleus.
2. Positively charged
3. Move slowly
Beta particles
1. Consists of electrons.
4. Has low
penetrating power.
5. Attracted by
negative charges.
6. Slightly deflected
by a magnetic field.
7. Has large mass
4. Has high
penetrating power.
5. Attracted by
positive charges.
6. Easily deflected by
a magnetic field.
7. Very light
2. Negatively charged
3. Move very quickly
Gamma particles
1. Consists of electromagnetic
waves.
2. Neutral
3. Move at the speed of
8
-1
Light ( 3 x 10 ms )
4. Has very high
penetrating power.
5. Not affected by positive or
negative charges.
6. Not deflected by a
magnetic field.
7. Has no mass
Radioisotopes
1. Isotopes are atoms of the same elements that have similar proton number but different
nucleon number. This lead to the difference in chemical characteristics.
2. Radioisotopes are the isotopes that emit heat energy and radiation.
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3. Examples of radioisotopes are:
Radioisotopes
Number of protons
Number of neutrons
Nucleon number
Carbon-14
6
8
14
Carbon-12
6
6
12
Uranium-234
92
142
234
Uranium-235
92
143
235
Uranium-238
92
146
238
*Isotopes of carbon are Carbon-12 and Carbon-14.
*Isotopes of Uranium areUranium-234, Uranium-235 and Uranium-236.
Uses of radioactive substances
Radioactive substances are widely used in agriculture, medicine, archaeology, food
preservation and industries.
 Agriculture
Example: Gamma rays are used to sterilise insects.
Therefore pest population could be reduced.
 Medicine
Example: Gamma rays are used to sterilise medical tools and equipments.
Cobalt-60 is used to kill cancer cells in radiotherapy.
 Archaeology
Example: Carbon-14 is used ‘carbon dating’ i.e to estimate the age of
organic materials such as wood and artifacts.
 Food preservation
Example: Gamma rays are used to kill microorganisms and preserve food without
destroying the nutrients in the food.
 Industries
Example: Gamma rays from cobalt-60 are used to detect cracks in metals.
6.2 PRODUCTION OF NUCLEAR ENERGY AND ITS USES
1. Nuclear energy could be produced by:
a. nuclear fission
b. nuclear fusion
Nuclear fission
a. Example: Uranium-235
- nucleus of the atom splits and releasing energy, radioactive
rays and more neutrons.
- this process goes on to produce a chain of nuclear fission.
- Use: In nuclear power station
- energy is used to produce steam that turns turbine (energy does not come from
coal or diesel or gas). Electricity is produced.
Nuclear fusion
-
In nuclear fusion, the reaction is to combine radioactive atoms.
Energy is released when nuclei fuse together.
- Example: The process that occurs in sun core where
hydrogen atoms fuse together to form helium.
- This process is still not practised in normal life because
of the difficulty to produce container that can hold
compressed hydrogen at very high temperature
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The process of generating electricity from nuclear energy.
1.
2.
3.
4.
5.
6.
The process of generating electricity from nuclear energy is carried out in nuclear reactor.
The nuclear reactor is designed to let nuclear fission of radioactive substances to occur
continuously.
Continuous nuclear fission can produce a large amount of energy.
The energy released from nuclear fission heats up the water in the vessel and produces
steam.
Steam turns the turbine.
The turbine is connected to electric generator that produces electricity.
Effects of nuclear energy production
1.
Radioactive substances can cause positive effects and also negative effects on living
things.
Positive effects
1. A source of non-renewable energy.
2. Does not pollute environment.
3. Can fulfill the higher demand of energy.
4. Have many uses in daily lives.
Negative effects
1. Nuclear leakage and improper disposal of
radioactive waste can cause pollution.
2. Can kill body cells.
3. Can cause cancer.
4. Can cause abnormality in foetus.
The need and the correct way of handling radioactive substances and radioactive waste.
1.
Since radioactive substances and wastes can harm us, we need to handle them
properly.
2. Radioactive substances and wastes must be kept in proper containers to prevent leakage.
3. People who are handling radioactive substances directly or indirectly need to:
a. wear protective attire filled with lead.
b. wear film badge that can measure the degree of exposure to radiation.
c. use remote control equipment to move radioactive substances.
d. have regular medical check-up to maintain good health.
4. Radioactive symbol is used to warn people of the presence of radioactive substances nearby.
Radioactive symbol
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PAPER 1
1. What is radioactive substance ?
A.
B.
Substance with unstable nuclei
Substance with a stable nuclei
C.
Substance with unstable atoms
D. Substance with a stable atoms
2. Which of the following is the rays emit by radioactive substances decay?
A.
B.
C.
D.
Alpha- rays, x-rays and beta-rays
X-rays, beta-rays and gamma-rays
Beta-rays, x-rays and gamma- rays
Alpha rays , beta rays and gamma rays
3. Which of the following is the arrangement of ,  and  ray in ascending order
according to their penetrating power?
,  , 
 , , 
A.
B.
4.
C.
D.
, , 
 , , 
Which of the following is true about the process of radioactive decay?
A.
B.
Heat energy is absorbed during the decay process
A more stable radioactive substance decays to form a less stable
substance
C. Radioactive radiations are produced during the process of radioactive
decay
D. The process of radioactive decay is influenced by the surrounding
temperature.
5.
The diagram shows two types of radiations passing through an electric field.
+
.
What are the radiations?
A.
B.
C.
D.
Gamma rays and X-ray
Beta particles and gamma rays
Alpha particles and gamma rays
Alpha particles and beta particles
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6.
Which of the following materials can be used to stop the gamma radiation?
A
B
C
D
7.
A thick paper
A sheet of paper
A thick lead block
A thin aluminium sheet
Which of the following is true about alpha rays ?
A
B
C
D
8.
It is not dangerous rays
Deviate to the negative pole
Show the highest penetrating power
Can be stop by using thick concrete block only
The information shows the characteristics of P.




Positively charged
Deflected by an electrical and magnetic fields
High ionization power
Weak penetrating power
What is P?
A.
B.
C.
D.
9.
Which of the following radioactive material is used in heart pacemakers?
A.
B.
C.
D.
10.
Cobalt – 60
Iodine – 123
Plutonium – 238
Uranium – 238
Which of the following is used in atomic bomb?
A.
B.
C.
D.
11.
Beta radiation
Alpha radiation
Gamma radiation
Infra red radiation
Nuclear fusion
Radioactive decay
Controlled chain reaction
Uncontrolled chain reaction
Which of the following is the usage of gamma radiation in medical field?
A.
B.
C.
D.
To kill cancerous cells
To kill bacteria in food
To determine the age of artifacts
To detect the leakage in underground piping
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12.
The information shows three substances.
 Carbon – 14
 Cobalt - 60
 Iodin-131
What are the substances?
A.
B.
13.
Beta radiation
Gamma radiation
Neutrons
Protons
C.
D.
Electrons
Nucleus
X-ray
Alpha radiation
C.
D.
Beta radiation
Gamma radiation
, , 
, , 
C.
D.
 , , 
 , , 
Which of the following radiation can be blocked by a piece of aluminium ?
A.
B.
19.
C.
D.
Which of the following is the correct sequence of radioactive particles in descending
order of penetrating powers?
A.
B.
18.
X-rays
Alpha radiation
Which of the radioactive radiation is not deflected by electrical field?
A.
B.
17.
Alpha rays have no charge
Beta rays is negatively charges
Gamma rays can be deflected by an electrical field
The penetrating power of gamma rays is the lowest
What type of particles is beta radiation ?
A.
B.
16.
Radioisotope
Non-metal
Which of the following is the particles of Helium ions?
A.
B.
15.
C.
D.
Which of the following statements is true about the characteristics of radioactive?
A.
B.
C.
D.
14.
Alloy
Metal
X- ray
Beta
C.
D.
Alpha
Gamma
Which of the following is the characteristic of beta radiation ?
A.
B.
C.
D.
Is an electron
Has a positive charge
Can penetrate a piece of thick aluminium sheet
Has a higher ionization power than alpha radiation
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20.
Which of the following radioactive radiation is used to determine the thickness of
paper, plastic or a sheet of metal?
A.
B.
21.
Beta radiation
Gamma radiation
Oxygen – 16
Carbon – 12
C.
Sodium - 23
D. Cobalt – 56
What is the particle used in nuclear fission ?
A.
B.
23.
C.
D.
Which of the following radioisotope is radioactive substance?
A.
B.
22.
X-ray
Alpha radiation
Proton
Neutron
C.
D.
Electron
Nucleus
Which of the following pair is correct about the radioactive substances and
their uses ?
A
B
C
D
Radioactive substance
Sodium – 24
Iodine – 131
Cobalt – 60
Plutonium - 238
Use
To treat cancer
To study the damage of pancreas
To detect blockages in the blood vessel
Source for battery used in the pace maker
24. The diagram shows the penetrating power of some radioactive rays.
paper
Aluminium
R
What is ray R ?
A.
B.
25.
X –ray
Alpha ray
C.
D.
Beta radiation
Gamma radiation
Which of the following about the use of nuclear energy as the alternative source
of energy is correct?
A
B.
C.
D.
It is safe
It is polluting the environment
It fulfill the higher demand of energy
The cost of generating electricity is cheaper
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26. The diagram shows the sequence of energy changes that occur in a nuclear
generator station.
Nuclear
energy
Energy
X
Energy
Y
Kinetic
energy
What type of energy that represented by X and Y?
A
B
C
D
27.
Cobalt – 60
Uranium – 235
To activate the process
To control the process
C.
D.
To generate power
To clean the reactor
Nuclear fusion
Nuclear fission
C.
D.
Nuclear reactor
radioactive decay
What happens to the nucleus during nuclear fission?
A.
B.
C.
D.
31.
C.
D.
Which of the following process used hydrogen isotopes?
A.
B.
30.
Radium – 226
Carbon – 14
What is the purpose of using graphite rods in nuclear reactors during the
nuclear fission of uranium ?
A.
B.
29.
Energy Y
Heat
Potential
Chemical
Electrical
Which of the following radioisotopes used in nuclear fission?
A.
B.
28.
Energy X
Kinetic
Chemical
Kinetic
Heat
Splits into two smaller nuclei
Splits into many smaller nuclei
Splits into protons and neutrons
Splits into two equal size nuclei
What is the function of Geiger Muller counter?
A.
B.
C.
D.
To detect radioactive radiations
To block radioactive radiation
To generate electrical energy
To control the nuclear reaction in a nuclear reactor
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32. Which of the following radioactive substance is used to detect pipe leakages ?
A.
B.
33.
C.
D.
Gamma radiation
Infra-red radiation.
Uranium
Carbon – 14
C.
D.
Cobalt - 60
Sodium – 24
X – ray
Beta radiation
C. Alpha radiation
D. Gamma radiation
.
Which of the following apparatus must be worn by people who handle
radioactive materials?
A.
B
C.
D.
37.
Alpha radiation
Beta radiation
Which of the following can be used to kill or sterile insect pests?
A.
B.
36.
Sodium –24
Phosphorus – 32
What is the type of radioactive substances used in radiotherapy
treatment ?
A.
B.
35.
C.
D.
Y radiation is used to delay the ripening of fruits and vegetables.
What is Y radiation?
A.
B.
34.
Cobalt – 60
Carbon – 14
Protective attire
Ordinary clothes
A glass goggle only
A Geiger-Muller counter
Which of the following is the effect of radiation leakage?
A.
B.
C.
D.
Eye cataract
Destroy the body cells
Depletion of ozone layer
Corrosion of the building
38. The diagram shows a symbol.
What is the symbol?
A.
B.
Industrial waste
Explosive substance
C.
D.
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Gas leakage
Radioactive substance
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39.
Which of the following is used to detect brain tumor ?
A.
B.
40.
C.
D.
Transportation.
Telecommunication
Lead metal
Glass prism
Llitmus paper
Geiger- Muller counter
Goiter
Mutation
Dysentery
Kwasyiorkor
Which of the following is the correct way of disposing radioactive waste?
A.
B.
C.
D.
44.
Astronomy
Medicine
What is the effect of radioactive radiation?
A.
B.
C.
D.
43.
Cobalt - 60
Phosphorus – 32
Which of the following is used to detect radioactive radiation?
A.
B.
C.
D.
42.
C.
D.
Which of the following field involve the use of radioactive substances?
A.
B.
41.
Sodium - 24
Barium – 138
Throw it into the river
Neutralise all the radioactive waste
Put radioactive substances into the rubbish bin after use
Keep in a closed concrete container and disposed into the deep sea.
What will be released when the nuclei combine during the process of nuclear
fusion?
A.
B.
Light
Water
C.
D.
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Oxygen
Carbon Dioxide
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PAPER 2
SECTION B
1.
Diagram 1 shows the radioactive decay of a nucleus
R
Radioactive
radiation
Radioactive
atom
S
DIAGRAM 1
a) What is meant by radioactive decay?
……………………………………………………………………………………
…………………………………………………………………………………….
(2 marks)
b) Name three radioactive particles/rays which are emitted during the
radioactive decay.
……………………………………………………………………………………
(1 mark)
c) If these radioactive particles/rays are in an electric field, which
particles/rays can go through the field without any deflection.
……………………………………………………………………………………
(1 mark)
d)
Give the reason for your answer in (c).
….………………………………………………………………………………….
……………………………………………………………………………………..
(1 mark)
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2.
Diagram 2 shows the deflection of radioactive radiations.
+ R:……………….
Q:………………..
.
:……………….
P:………… …….
DIAGRAM 2
a)
Label the radiation P,Q and R.
b)
What are the electrical charges for
(3 marks)
P :……………….. Q:………………………. R:……………………
(3 marks)
c)
Why are P, Q and R moving through three different paths?
………………………………………………………………………………………
………………………………………………………………………………………
(1 mark)
d) i) Which radiation is the most dangerous to our body?
……..………………………………………………………………………………
(1 mark)
ii) Give two characteristics that make the radiation Q is the most
dangerous.
…………………………………………………………………………………….
……………………………………………………………………………………
(2 marks)
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SECTION C
1. a)
Give two usage of radioactive substances and the example of element used.
[ 4 marks]
b)
Diagram 3 shows an examples of elements.
Uranium
Cobalt-60
Elements
Sodium-24
Iodine -131
DIAGRAM 3
Study the above examples of substances. You are required to develop a concept
of a radioactive substances.
Your answer should be based on the following aspects:
 Identify two common characteristics of radioactive substances.
 Develop an initial concept of a radioactive substances.
 Give other example of a radioactive substances and the reason for your
choice
 Give one example of a non- radioactive substances and the reason for your
choice.
 State the actual concept of a radioactive substances.
[6 marks]
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