Test Bank General Chemistry, 10th edition 16
A)
1 only
B)
2 only
C)
3 only
D)
1 and 2
E)
1, 2, and 3
53. Which of the following corresponds to the most rapid nuclear decay?
A)
t1/2 = 1.0 103 min
B)
t1/2 = 1.0 109 year
C)
k = 1.0 10–3/year
D)
k = 1.0 10–1/day
E)
k = 1.0 10–5/s
54. Which of the following statements is true?
A)
As a radioactive isotope decays, its half-life decreases over time and its rate of
disintegration remains the same.
B)
As a radioactive isotope decays, its half-life remains the same and its rate of
disintegration remains the same.
C)
As a radioactive isotope decays, its half-life remains the same and its rate of
disintegration increases over time.
D)
As a radioactive isotope decays, its half-life remains the same and its rate of
disintegration decreases over time.
E)
As a radioactive isotope decays, its half-life decreases over time and its rate of
disintegration decreases over time.
55. If a sample of the radioactive nuclide 139Cs has an activity of 0.0293 Ci, what is the
instantaneous rate of decomposition of 139Cs in terms of grams per second? The mass of
139Cs is 138.9134 amu. (1 Ci = 3.700 1010 disintegrations/s, 1 amu = 1.66054 10–24 g)
A)
g/s
B)
g/s
C)
g/s
D)
g/s
E)
g/s
56. What is the percent activity of a radioactive sample (relative to its original activity) that has
undergone four half-lives of decay?
A)
6.25%
B)
25.0%
C)
12.5%
D)
3.13%
E)
75.0%
57. After 3.2 hours, of the initial amount of a particular radioactive nuclide remains
unchanged. What is the half-life of the nuclide?
A)
32 min
B)
45 min
C)
60 min
D)
74 min
E)
20 min
58. Consider a certain type of nucleus that has a rate constant of 2.56 10-2 min-1. Calculate the
time required for the sample to decay to one-fourth of its initial value.
A)
27.1 min
B)
33.8 min
C)
0.0512 min
D)
54.1 min
E)
2.56 min
59. The rate constant for the decay of a radioactive isootope is 4.226 10–3 / day. What is the
half-life of of this isotope?
A)
328.0 days
B)
410.0 days
C)
82.00 days
D)
164.0 days
E)
none of these
60. Use the following table to assist in answering the question below.
Nuclide
Half-Life
Uranium-238
4.51 109 years
Uranium-234
2.48 105 years
Thorium-230
8.0 104 years
Radium-226
1.62 103 years
Lead-210
20.4 years
The rate constant for the decay of unstable nuclide X by alpha-particle emission is
1.17 10-6 / day. What is the identity of X?
A)
radium-226
B)
thorium-230
C)
uranium-238
D)
uranium-234
E)
lead-210
61. Iodine-131 decays by beta emission with a half-life of 8.04 days. What is the decay constant
for iodine-131?
A)
/h
B)
/min
C)
/s
D)
/day
E)
/h
Test Bank General Chemistry, 10th edition 19
62. A sample of a radioactive isotope is found to have lost 39.9% of its original activity after
8.57 days. What is the decay constant of this isotope?
A)
0.0594 d−
B)
0.107 d−
C)
4.36 d−
D)
0.0392 d−
E)
0.478 d−
63. What is the decay constant for a particular radioactive element that has a half-life of 5.55
years?
A)
0.161/year
B)
0.113/year
C)
7.18 10–3/h
D)
25.8/s
E)
0.125/year
64. The half-life of the radioactive nuclide is 9.0 min. What is the activity of a 9.8-
sample of ? The molar mass of is 78.921 g/mol. (1 Ci = 3.700 1010
disintegrations/s)
A)
Ci
B)
Ci
C)
Ci
D)
Ci
E)
Ci
65. The half-life of the radioisotope 158Eu is 0.77 h. How much time is required for a 160.0-g
sample of 158Eu to decay to 1.29 g?
A)
6.0 h
B)
4.0 h
C)
3.0 h
D)
2.3 h
E)
5.4 h
66. The half-life of 42K is 12.5 h. How much will remain after 81 h if the original sample
contained 256 g of 42K?
A)
22 g
B)
2.9 g
C)
17 g
D)
19 g
E)
11 g
67. The isotope 210Pb has a half-life of 22 years. What percentage of a pure 210Pb sample
prepared in April 1937 remains in April 2003?
A)
13%
B)
26%
C)
31%
D)
21%
E)
38%
68. Iodine-131, which is used to treat thyroid cancer, has a half-life of 8.04 days. How much
time is required for 84% of the isotope to decay?
A)
21 days
B)
7 days
C)
41 days
D)
53 days
E)
2 days
Test Bank General Chemistry, 10th edition 21
69. The half-life of phosphorus-33 is 25 days. How much of a 128-g sample will remain after
150 days?
A)
2.0 g
B)
16 g
C)
1.0 g
D)
8.0 g
E)
4.0 g
70. A 4.50-mg sample of a newly discovered radioactive nuclide was analyzed and found to
contain only 3.25 mg after a period of 31.9 h. What is the half-life of the nuclide?
A)
77.3 h
B)
67.9 h
C)
72.2 h
D)
12.8 h
E)
16.8 h
71. Strontium-90 is produced in nuclear explosions. It can replace calcium in the bone. The
half-life of 90Sr is 27.7 years. If the activity of 90Sr in the bones of an exposed person were
90 disintegrations per second, how long would it take the activity of 90Sr to decrease to 8.1
disintegrations per second?
A)
96 years
B)
68 years
C)
46 years
D)
57 years
E)
75 years
72. The half-life of neptunium-231 is 50.0 min. How many minutes will it take for 5.0 g of this
isotope to decay to 0.20 g?
A)
1.60 102
min
B)
2.30 102
min
C)
1.50 102 min
D)
4.00 102 min
E)
1.00 102
min
73. A radioactive isotope undergoes decay by emission of a positron. After 2.00 h, 5.880% of
the initial amount of the isotope remains undecayed. What is the half-life of this isotope?
A)
45.0 min
B)
29.3 min
C)
90.0 min
D)
15.0 min
E)
60.0 min
74. A living tree contains 14C (half-life, 5730 years) and has a specific activity of 750 counts per
hour. A wooden artifact recovered from an archeological site gives a count of 210 counts
per hour. The age of this artifact is most nearly
A)
47,000 years.
B)
4,600 years.
C)
11,000 years.
D)
22,000 years.
E)
5730 years.
75. What assumption must be true for radiocarbon (14C) dating to be useful?
A)
14C has the same mass as 12C.
B)
A constant concentration of 14C is maintained in living plants and animals through
equilibration with atmospheric levels of 14C.
C)
The sample cannot have been chemically altered prior to the analysis.
D)
14C always decays at the same rate.
E)
14C is nonradioactive.
Test Bank General Chemistry, 10th edition 23
76. Which of the following statements is(are) true of radioactive carbon-14?
1.
It undergoes alpha decay.
2.
It is produced in the upper atmosphere by cosmic radiation.
3.
It has a constant concentration in living matter.
A)
1 only
B)
2 only
C)
3 only
D)
1 and 3
E)
2 and 3
77. A sample of wood from an Egyptian mummy case gives a count of 8.4 cpm/gC (counts
per minute per gram of carbon). How old is the wood? (The initial decay rate of is
15.3 cpm/g C, and its half-life is 5730 years.)
A)
6.01 103
years
B)
7.46 103
years
C)
4.96 103
years
D)
2.48 103
years
E)
none of these
78. If a tree dies and the trunk remains undisturbed for 14821 years, what percentage of original
is still present? (half-life of = 5730 years)
A)
33%
B)
25%
C)
83%
D)
17%
79. Which of the following statements is incorrect?
A)
Isotope dilution is a technique used to determine the quantity of a substance in a
mixture by adding a known amount of an isotope to it.
B)
Isotope dilution was used to elucidate the biological pathways of photosynthesis.
C)
Isotope dilution may be used to determine the amount of vitamin B12 in food.
Test Bank General Chemistry, 10th edition 24
D)
A radioactive tracer is a very small amount of a radioactive isotope added to a
system used to study the chemical, physical, or biological processes of a system.
E)
Neutron activation analysis is an analysis of elements in a sample based on the
conversion of stable isotopes to radioactive isotopes by bombarding a sample with
neutrons.
80. Which of the following radioactive isotopes is not commonly used in medical applications?
A)
technetium-99m
B)
iodine-131
C)
strontium-90
D)
cobalt-60
E)
thallium-201
81. Metastable isotopes, such as Technetium-99m and those produced from neutron activation
analysis decay by what process?
A)
gamma emission
B)
alpha emission
C)
beta emission
D)
positron emission
E)
all of the above
82. What is the energy change for the following nuclear bombardment reaction?
(c = 3.00 108 m/s, 1 amu = 1.66054 10–27 kg, 1 MeV = 1.602 10–13 J)
Particle
Mass (amu)
1.008665
4.00260
39.96400
42.96115
A)
MeV
B)
MeV
C)
MeV
D)
3.00 MeV
E)
MeV
83. How much energy is released when 3.00 metric tons of 2H2 gas undergoes nuclear fusion?
(1 metric ton = 1000 kg, c = 3.00 108 m/s, 1 amu = 1.66054 10–27 kg)
2H + 2H → 3He + 1n
Particle
Mass (amu)
1.008665
2.01400
3.01603
A)
J
B)
J
C)
J
D)
J
E)
J
84. What quantity of energy is released per gram of U-235 based on the following neutron
induced fission of U-235? (c = 3.00 108 m/s)
Particle
Mass (amu)
1.008665
235.043922
136.9253
96.910950
Test Bank General Chemistry, 10th edition 26
A)
7.62 1010 J/g U-235
B)
7.62 1013 J/g U-235
C)
1.79 1010 J/g U-235
D)
1.79 1013 J/g U-235
E)
3.10 1011 J/g U-235
85. Relative to the sum of the masses of its constituent nucleons (neutrons + protons), the mass
of a nucleus is
A)
always greater.
B)
sometimes the same and sometimes smaller.
C)
always smaller.
D)
always the same.
E)
sometimes greater and sometimes smaller.
86. One of the first nuclear bombs based on the fission of U-235 had a maximum yield of 7.5
x1013 J. If the fission of U-235 releases 1.8 1013 J/mol, approximately what mass of U-
235 was used in this bomb? (U-235 has a molar mass of 235.04 g/mol)
A)
9.8 102 g U-235
B)
56 g U-235
C)
0.018 g U-235
D)
0.0010 g U-235
E)
2.3 102 g U-236
87. Which of the following nuclides has the highest nuclear binding energy per nucleon?
A)
B)
C)
D)
E)
88. What is the mass defect of ?
Particle
Mass (amu)
11.0216
1.00728
1.00867
0.00055
A)
–0.1055 amu
B)
–1.685 amu
C)
–0.0704 amu
D)
–4.1051 amu
E)
–0.1707 amu
89. If 1 mol of oxygen-16 were formed from protons and neutrons, 0.1366 g of mass would be
lost. What can best account for this loss?
A)
Converting from the atomic scale (in atomic mass units) to the macroscopic scale
(in grams) can often cause minor errors to occur.
B)
The process was so exothermic that the system lost energy, which means that it
also lost mass.
C)
This is impossible because of the law of conservation of matter (so mass must be
conserved).
D)
When fission occurs, the nuclei remaining always have a smaller mass.
E)
Both a and c are correct.
90. What is the nuclear binding energy per nucleon of a atom? (c = 3.00 108 m/s,
1 amu = 1.66054 10–27 kg)
Particle
Mass (amu)
65.926036
1.00728
1.00867
0.00055
A)
J/nucleon
B)
J/nucleon
C)
J/nucleon
D)
J/nucleon
E)
J/nucleon
91. Enriched uranium is uranium that has a greater proportion of
A)
lead-207.
B)
lead-208.
C)
deuterons.
D)
uranium-235.
E)
uranium-238.
92. Which of the following statements is(are) true for the fission of uranium-235?
A)
The electron is captured by the nucleus, which becomes unstable.
B)
The nuclides produced are more stable than the uranium nuclide.
C)
The nuclides produced are individually heavier than the uranium nuclide.
D)
The products include neutrons.
E)
Two of these statements are true.
93. It is possible that the world’s energy problem could be solved by making use of the fusion
reaction of deuterium and tritium. Which of the following reaction equations corresponds to
that process?
A)
B)
C)
D)
E)
94. Which of the following statements regarding a fission based nuclear reactor is not correct?
A)
A nuclear fission reactor uses the heat energy released by the fission of U-235 to
produce steam.
B)
The control rods in a nuclear reactor contain materials which absorb neutrons.
C)
The moderator in a fission reactor slows down the neutrons produced from the
fission of U-235.
D)
(heavy water), graphite, and H2O (light water) have been used as moderators
in fission reactors.
E)
The uranium dioxide fuel pellets used in a U.S. light-water reactor are made up
mostly of the U-235 isotope.