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1. What are the chemical designations for each of the following isotopes? Also indicate the
numbers of protons, neutrons and electrons each isotope has.
a) carbon-12 b) copper-65
c) magnesium-25 d) nickel-60
e) uranium-238
2. The equations below have unknowns indicated by x and y. What are the values for x and y for
each circumstance?
3. The following list of nuclear reactions occur either by alpha or beta decay. Determine the type
of decay for each circumstance.
4. Polonium-84 is the end result in the decay sequence shown below.
For the transmutations labeled (a) to (e), determine the type of decay process present.
5. The mass of a radioisotope with half-life of 20 h is 320 g. Calculate the remaining mass of this
isotope after:
a) 40 h b) 80 h c) 5 d
6. An experiment starts with 140 g of strontium-82. If the half-life of strontium-82 is 25.0 days,
how long will the experiment have to run in order to have only 17.5 g of strontium left?
7. The radioactivity of a 1 m3 sample of radon gas was measured at 10 Bq. Later the radioactivity
was measured at 2.5 Bq. If the half-life of radon gas is 4 d, how much time has elapsed
between measurements?
8. In recent years, scientists have discovered that the Earth's magnetic field has shifted in position
over time. One result of the shifting of the Earth's magnetic field, has been a variance in the
amount of cosmic radiation that reaches the Earth's surface. Some people argue that this shift
in cosmic radiation, would put into question the accuracy of the carbon-14 dating method.
Explain why these people would think this.
9. The following results were recorded for an experiment designed to determine the half-life of a
radioisotope.
a) Plot a graph of the data collected.
b) What is the half-life of this radioisotope?
c) Use your graph to predict the activity that would be present after:
1) 7 h 2) 19 h 3) 26
10. Neutrons are often used instead of alpha particles when nuclear reactions are to be produced.
Explain why scientists would prefer neutrons.
11. Complete the following nuclear reactions.
12. Sodium-20 atoms are bombarded with protons. It is noted that alpha particles are emitted in
the process. Determine the atomic mass and atomic number of the resulting nucleus. What is
the nuclear equation that represents the process involved?
13. Particle bombardment is often used to produce artificial transmutations. These experiments
often produce protons, deuterium nuclei, or even neutrons. For the following particle
bombardment nuclear reactions, determine the missing information.
14. A 2.0 kg object absorbs 42 J of energy. The origin of the energy is a radioactive source.
What dose in grays does the 2.0 kg object receive?
15. How much energy is produced if these masses are completely converted to energy?
a) 2.0 kg b) 40 g c) 0.1 mg
16. What is the rate of mass loss of the sun given that the sun puts out 4.0 X 1026 J of energy
every second? You can assume that all this energy is a result of fusion processes.
17. An experimental atomic bomb, when exploded, produces 8.0 X 1013 J of energy. The fission
of one atom of uranium-235 produces 3.2 X 10-3 J of energy.
a) If the bomb is a fission bomb using uranium-235, how many uranium atoms underwent
fission?
b) The energy produced in nuclear reactions comes from a conversion of mass to energy.
How much mass is converted to energy in this bomb?
18. In order to build a nuclear bomb, one must insure that a minimum mass of fissionable material
comes together. This minimum mass is called the critical mass. Why is a critical mass
necessary to produce a chain reaction?
19. You have two blocks of porous uranium. One is located in air, and the other is located in
water. Which situation is most likely to sustain a chain reaction. Explain your answer.
20. Nuclear power reactors cannot be located just anywhere. What factors must be taken into
consideration when deciding upon a location for construction of a nuclear reactor?
21. Some countries have disposed of nuclear waste by encasing it in concrete and dumping it in
the ocean. Why is this disposal method a bad idea?
22. Canada has proposed that radioactive wastes be disposed of by burial in the Canadian Shield.
Explain why this would protect the present generation of human beings. Do a risk benefit
analysis of this method of disposing of nuclear wastes.
23. When Canada sells CANDU reactors to other countries, we are also selling them the
capability to construct nuclear bombs.
a) Explain why we are also selling bomb technology.
b) What kinds of nuclear reactors are the best for producing extra fissionable material
for bombs?
24. In order to cause fusion, extremely high temperatures must be maintained. Explain why this
is so.
25. Explain why sustained fusion cannot take place in a normal container.
26. When comparing fission and fusion, fission produces radioactive isotopes, but fusion produces
a fairly clean reaction. With a hydrogen bomb, most of the energy is produced by fusion.
Explain why radioactive "fallout" is still a problem with a hydrogen bomb.
27. The accepted theory of star formation has a vast cloud of hydrogen being drawn together by
the force of gravity. As collapse occurs, the density of the cloud increases, and eventually
nuclear fusion starts. Explain why fusion starts.
January 20, 2014
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