East Doncaster Secondary College
UNIT 1 PHYSICS
RADIOACTIVITY AND NUCLEAR ENERGY - TEST
NAME: ....................………..............................
SECTION 1: MULTIPLE CHOICE - circle the most appropriate response - 1 mark each.
1.
In the nucleus , 238
92 U there are
A.
C.
2.
99
42
92 protons and 238 neutrons
146 protons and 92 neutrons
Mo decays to form 99
43Tc .
A.
C.
a neutron
a beta particle
B.
D.
92 protons and 146 neutrons
238 protons and 92 neutrons
The type of radioactive decay observed is
B.
an alpha particle
D.
a gamma particle
3.
A radioactive isotope has a half-life of 10 days. What is the time required for the activity of the isotope to fall
to a 16th of its original value.
A. 20 days
B.
50 days
C.
40 days
D.
160 days
4.
The harmful effects of radiation are largely attributable to the creation in the body of
A. chemically reactive ions
B.
alpha particles
C.
beta particles
D.
toxins
5.
The unit of absorbed dose of radiation (the Gray) is measured in
-1
A. J m
B.
Jm
-1
C.
J kg
D.
J kg
6.
The dose equivalent of radiation (measured in sieverts) is calculated by multiplying the absorbed dose by a
quality factor which describes
A. the time over which the radiation is received
B.
the type of radiation received
C.
the background count
D. the area of the body that is effected
7.
A
Z
X  Z A1Y  10 e represents what type of radioactive decay?
A.
B.
C.
D.
alpha particle
beta particle
gamma ray
neutron emission
8.
A nucleus becomes increasingly unstable when
A. there are more protons than electrons
B.
there are more protons than alpha particles
C.
there are more neutrons than protons
D. it decays alpha particles from the nucleus
9.
Alpha particles can be best described as
A. a double-charged hydrogen nucleus
B.
an electron
C.
a pulse of electro-magnetic radiation
D. a double-charged helium ion
10.
233
91
Pa decays by a series of radioactive emissions to
225
89
Ac
How many of what type of particles are emitted in the process?
A. one alpha and two betas
B.
one alpha and four betas
C.
two alphas and two betas
D.
two alphas and four betas
Atomic & Nuclear test.doc
East Doncaster Secondary College
11.
Uranium-235 releases energy in a process called fission. Fission is
A. the addition of a neutron to the nucleus
B.
the splitting of the nucleus into two smaller nuclei
C.
the release of gamma radiation
D. the combination of two smaller nuclei to form a larger one
12.
The source of energy released in fission is
A. the mass lost in the reaction
B.
the chemical reaction of the nucleus with a neutron
C.
the burning of the nucleus in oxygen
D. the mass gained in the reaction
13.
Which of the following best describes the role of the moderator in a nuclear reactor?
A. It removes excess neutrons if too much power is being generated
B.
It changes the nuclear energy generated into useable forms
C.
It slows down some of the fast neutrons
D. It absorbs products that could poison the fuel rods.
14.
Einstein's famous mass/energy equation is E = mc . The c represents
A. the speed of sound
B.
the energy produced
C.
the speed of light
D.
the destroyed mass
15.
Fission produces neutrons. Typically, how many neutrons are produced per fission event?
A. 1
B.
2 or 3
C.
235
D.
92
16.
Which of the following best describes the role of the control rods in a nuclear reactor?
A. They remove excess neutrons if too much power is being generated.
B.
They change the nuclear energy generated into useable forms.
C.
They slow down some of the fast neutrons.
D. They absorb products which could poison the fuel rods.
17.
Naturally occurring uranium contains approximately
A. 0.7% uranium-235
B.
0.7% uranium-238
C.
99% uranium-235
D.
7% uranium-235
18.
In 168 seconds the activity of a radioisotope falls to
2
A.
B.
C.
D.
1 th
of its original value. What is its half-life?
8
21 seconds
84 seconds
42 seconds
56 seconds
19.
For nuclear reactions, energy is usually measured in MeV. What does MeV stand for?
A. mega electron volt
B.
milli electron volt
C.
minute energy value
D. mega energy volt
20.
There are three main naturally occurring decay series. They all end up with a stable isotope of
A. Strontium
B.
Lead
C.
Plutonium
D.
Actinium
Atomic & Nuclear test.doc
East Doncaster Secondary College
SECTION 2: SHORT ANSWERS (marks are as indicated)
1.
A certain radio-isotope has a half-life of 8.0 hours. If 48 g of the isotope is initially present, how
must of the original isotope is left after 24 hours?
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2.
The isotope in Q. 1 decays by alpha emission. Explain the changes that occur in a nucleus during
alpha decay and state the changes (if any) to the mass number and the atomic number.
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3.
List the three types of radioactive decay in order from the most ionising to the least ionising and
explain why this is so.
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4.
Explain how a thermal nuclear reactor can achieve a controlled rate of fission. You should mention:
neutrons, chain reaction, control rods, the average number of new fission events.
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Atomic & Nuclear test.doc
East Doncaster Secondary College
5.
An experiment was performed to determine the half-life of iodine-131. The following activities were
recorded at 12:00 p.m. (noon) on each observation day.
Observation day
Activity
0
9900
4
7050
8
4950
12
3500
16
2510
a) Plot a graph of the activity on the following set of axes. (1 mark)
activity
10,000
7,500
5,000
2,500
0
4
8
12
16
observation day
b) According to the graph, what is the half-life of iodine-131? .........................................(1 mark)
c) What would you expect the activity to be on day 24? ...................................................(1 mark)
d) Iodine (I-131) has an atomic number of 53. It beta decays to Xenon, Xe. Write the full decay
equation for this process. Include mass and atomic numbers of each nuclide.
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e) Iodine-131 also emits gamma radiation during its decay. Explain what this is and provide three
properties of gamma rays.
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6.
Explain briefly how a nuclear bomb can provide a vast amount of energy in a very short time.
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Atomic & Nuclear test.doc