59) In positron emission tomography (PET), a positron collides with an electron and the two particles
disappear in a burst of
A) an alpha particle and a gamma ray.
B) two beta particles.
C) a neutron and an alpha particle.
D) two gamma rays.
60) Which one of the following is most penetrating?
A) He nucleus
B) beta particle
C) gamma ray
D) visible light
61) Which type of radioactive emission is very similar to X-rays?
A) positron
B) electron
C) alpha
D) gamma ray
62) Radioactive alpha emitters pose the greatest potential health risk when they are
A) unshielded.
B) on the skin.
C) ingested.
D) all of the above
63) Alpha particles can be stopped by a
A) sheet of paper.
B) block of wood.
C) thin sheet of aluminum.
D) all of these
64) Gamma rays can be stopped by
A) a sheet of paper.
B) a thin aluminum sheet.
C) a block of wood.
D) several centimeters of lead.
65) Although Albert Einstein is considered one of the greatest scientists of all time, his work generally did
not involve much of an aspect that is traditionally associated with science. That aspect is
A) creativity.
B) mathematics.
C) theories.
D) experiments.
66) In the famous relationship: E = mc2, the symbol m represents
A) mass.
B) molecules.
C) momentum.
D) metastable.
67) The mass of a helium nucleus is slightly less than the sum of its parts (2 protons and 2 neutrons)
because
A) some of the mass is converted to binding energy.
B) some of the mass is given to electrons.
C) the mass of protons and neutrons are not precisely known.
D) the mass of a proton is larger than the mass of a neutron.
68) Which process will result in an increase in the binding energy per nucleon?
A) fission of large radioactive nuclei
B) fusion of small nuclei
C) both A and B
D) neither A nor B
69) The most stable elements have
A) a high binding energy per nucleon.
B) a low binding energy per nucleon.
C) a high proton to neutron ratio.
D) an atomic number above 92.
70) Nuclear fission is a process by which the nucleus of an atom
A) splits into two or more fragments spontaneously.
B) is induced to split into two or more fragments by some external source.
C) combines with another nucleus to produce a larger nucleus.
D) loses a proton with the release of a large amount of energy.
71) In the fission of uranium-235, which particle causes and propagates the chain reaction?
A) alpha particle
B) beta particle
C) neutron
D) electron
72) In nuclear fusion,
A) large unstable nuclei are fused together, and then split with the release of binding energy.
B) large, relatively unstable, nuclei are split releasing binding energy.
C) small, relatively stable, nuclei are split releasing binding energy.
D) smaller, relatively stable, nuclei are forced together to create a larger nucleus with the release of
binding energy.
73) The source of the energy produced by the sun is
A) the burning of fossil fuels.
B) the fission of uranium-235.
C) the fusion of primarily hydrogen.
D) unknown.
74) Critical mass is
A) the minimum amount of fissionable material that will sustain a chain reaction.
B) the maximum amount of fissionable material that will sustain a chain reaction.
C) the amount of fissionable material that produces the most energy when split.
D) the largest amount of fissionable material that can be obtained from isotopic enrichment.
75) The U.S. president who ordered the dropping of atomic bombs on the Japanese cities of Hiroshima
and Nagasaki was
A) Bill Clinton.
B) Harry Truman.
C) Dwight Eisenhower.
D) George Bush.
76) Naturally occurring uranium contains approximately what percentage of uranium-235, the isotope
that undergoes fission?
A) 0.72%
B) 10%
C) 50%
D) 100%
77) The often tedious process by which a naturally occurring mixture of isotopes is separated and
concentrated is called
A) isotopic transmutation.
B) isotopic ionization.
C) isotopic synthesis.
D) isotopic enrichment.
78) Stagg Field, at the University of Chicago, is where
A) nuclear fission was discovered.
B) radioactivity was discovered.
C) nuclear fusion was discovered.
D) the first nuclear pile was built.
79) Which of the following was NOT a goal of the Manhattan project?
A) to isolate enriched uranium-235
B) to produce plutonium-239
C) constructing a bomb based on nuclear fission
D) to determine the amount of uranium-235 needed for an atomic power plant
80) UF6 containing uranium-235 can be separated from UF6 containing uranium-238 because
A) compounds containing uranium-235 react differently than compounds containing uranium-238.
B) UF6 containing uranium-235 is lighter and will travel faster than UF6 containing uranium-238.
C) UF6 containing uranium-235 is lighter and will travel more slowly than UF6 containing uranium-238.
D) They cannot be separated.
81) Strontium-90 from nuclear fallout is a potential major long-term human health threat because
A) it is chemically similar to calcium, has a relatively long half-life, and is incorporated into bone.
B) it is chemically similar to calcium, has a relatively short half-life, and is incorporated into breast milk.
C) it is chemically similar to sodium, has a relatively long half-life, and collects in the liver.
D) it is chemically similar to sodium, has a relatively short half-life, and collects in the heart.
82) Iodine-131 from nuclear fallout is a potential major short-term human health threat because
A) it is concentrated in the thyroid and has a relatively long half-life.
B) it is concentrated in the thyroid and has a relatively short half-life.
C) it is chemically similar to calcium and has a relatively long half-life.
D) it is chemically similar to calcium and has a relatively short half-life.
22
83) Cesium-137 is both produced in nuclear fallout and has a half–life of 30 years. Cesium-137 is capable
of long-term effects because it is
A) chemically similar to calcium and is absorbed in the bones.
B) chemically similar to potassium and is taken up by living organisms as part of body fluids.
C) chemically similar to sodium and collects in the blood.
D) chemically similar to magnesium and collects in the blood.
84) Which scientist won a Nobel prize for chemistry in recognition of work involving the structure of
proteins, and the Nobel prize for peace for efforts in controlling nuclear weapons?
A) Bill Nye
B) Linus Pauling
C) Max Planck
D) Glenn Seaborg
85) Which of the following isotopes produced in fission bomb explosions poses the greatest health risk to
humans?
A) xenon-129
B) strontium-90
C) krypton-82
D) barium-138
86) Thermonuclear reaction
A) is a process in which a large nucleus spontaneously splits into two or more smaller nuclei.
B) is a process in which a large nucleus is bombarded with a neutron and then splits into two or more
smaller nuclei.
C) is a process in which smaller nuclei combine to form nuclei.
D) is a process used to generate electricity in nuclear power plants.
87) Which of the following isotopes is NOT considered to be a major threat to human health from nuclear
fallout?
A) cesium-137
B) hydrogen-2
C) iodine-131
D) strontium-90
88) Give a use for depleted uranium.
A) design jewelry
B) form car bodies
C) make coins
D) make armor plating
89) The nuclear synthesis of plutonium-239 was an important part of the effort to build an atomic bomb
during World War II because
A) plutonium-239 is required to cause uranium-235 to fission.
B) plutonium-239 is fissionable.
C) plutonium-239 has a longer half-life than uranium-235.
D) of all of these reasons
90) The factor that is NOT a detriment to the building of nuclear power plants is
A) the possibility of a “nuclear bomb-like” explosion.
B) the scarcity of 235U.
C) the disposal of nuclear wastes.
D) the high cost of the power produced.
91) Which of the following statements about nuclear power plants is NOT true?
A) They generate some of the electricity used in the United States and Europe.
B) The uranium fuel used contains about 3% of 235U.
C) The uranium fuel used contains over 90% of 235U.
D) They generate a considerable amount of radioactive waste.
92) Identify what is NOT a use of radioactive isotopes.
A) sterilization of suture material
B) medical diagnosis
C) treat diabetes
D) power for spacecraft
93) Identify which one was NOT a malfunction at a nuclear power plant.
A) A tornado tore a roof of the cooling plant resulting in a release of radioactive gas.
B) A partial meltdown of the core occurred.
C) A fire resulted in the release of radioactivity into the surrounding area.
D) An earthquake caused a tsunami, and flooded the nuclear plant. The cooling system failed, a partial
core meltdown occurred, and radioactive material was released.
94) Identify a problem with nuclear power plants.
A) must be built by water
B) spent fuel changed into weapons
C) must be built on a mountain
D) population wants in next door
11.2 True/False Questions
1) Over 55% of the radiation to which the average person is exposed comes from natural sources.
2) All isotopes with Z < 83 are radioactive.
3) Nuclear reaction rates are not affected by changes in temperature.
4) After one half-life, 50% of a radioactive sample will remain. After the second half-life, none of the
radioactivity will be left.
5) Radioactive dating can only be used to date very old objects.
6) The ratio of different isotopes of an element, such as oxygen-16 and oxygen-18, will always be the
same.
7) It will take three half-lives for all of a radioactive sample to decay.
8) Artificial transmutation can occur when nuclei are bombarded with small particles, such as alpha
particles, neutrons or other subatomic particles.
9) Radioactive isotopes and nonradioactive isotopes of an element react essentially identically.
10) Nuclear science has saved many more lives than have been destroyed by nuclear bombs.
11) Alpha particles will penetrate much farther into a sample than beta particles will.
12) A helium nucleus contains two protons and two neutrons. The mass of the helium nucleus is greater
than the combined masses of two protons and two neutrons because binding energy has been added.
13) Plutonium-239 can undergo nuclear fission.
14) Uranium-238 can undergo nuclear fission, but uranium-235 does not.
15) Strontium-90 from radioactive fallout poses a significant risk to human health because it is chemically
similar to calcium and can be incorporated into bone.
16) Iodine-131 from radioactive fallout will concentrate in the thyroid gland. However, it has only a short
half-life and therefore poses only minimal health risks to humans.
17) The percentage of electricity generated by nuclear power is much higher in the United States than in
Belgium.
18) The major reaction in the sun is the fusion of four hydrogen nuclei to produce a helium nucleus and
two positrons.
19) Nuclear power plants require fuel that has a higher percentage of Uranium-235 than needed for a
bomb.
20) A “dirty bomb” creates a nuclear explosion.
21) One way to decrease the volume of waste from spent nuclear rods is to dissolve the rods in ethanol.
11.3 Short Answer Questions
1) In the fission of uranium-235, which particle causes and propagates the chain reaction?
11.4 Essay Questions
1) What is transmutation?
2) Discuss why radioisotopes are used as tracers in medical diagnostics and research.
3) Rank the penetrating power of nuclear radiation from the least to most penetrating.
4) Compare and contrast nuclear fission and nuclear fusion.
5) What is isotopic enrichment and why was it a crucial step in the manufacture of the first atomic bomb?
6) Comment on three peacetime uses of nuclear energy.