67) The half-life of radioactive iodine-137 is 8.0 days. How many iodine nuclei are necessary to
produce an activity of 1.0 μCi? (1 Ci = 3.70 × 1010 Bq)
A) 2.9 × 109
B) 4.6 × 109
C) 3.7 × 1010
D) 7.6 × 1012
68) What mass of 14C, with a half-life of 5730 y, do you need to provide a decay rate of
The mass of 14C is 14.00 u, and 1 u = 1.6605 × 10-27 kg.
A) 1.70 × 10-12 kg
B) 5.38 × 10-19 kg
C) 3.84 × 10-20 kg
D) 8.68 × 10-13 kg
69) An old bone sample contains 321 g of carbon and has an activity of 947 decays/min due to
the carbon-14 in it. The half-life of carbon-14 is 5730 y. Assume that the activity of the
atmospheric carbon is, and has remained, 0.255 Bq per gram of carbon.
(a) How old is the sample?
(b) What will be the activity of the sample 2000 y from now, in decays per minute?
70) An archaeologist finds the 14C in a sample of of material to be decaying at 107 Bq. A
modern sample of the same material decays at 151 Bq,and assume this rate has also held in
the past. The half-life of 14C is 5730 years. How old is the sample?
A) 8980 years
B) 6230 years
C) 17,000 years
D) 8530 years
71) A sample of wood has been recovered by an archaeologist. The sample is sent to a
laboratory, where it is determined that the activity of the sample is 0.144 Bq/g. By comparing
this activity with the activity of living organic matter, which is 0.230 Bq/g, the scientist
determines how old the wood sample is, or more precisely, when the tree that the sample came
from died. Carbon-14 has a half-life of 5730 years. If the activity of living matter has been
constant over time, how old is the sample of wood?
A) 3870 years
B) 4250 years
C) 4590 years
D) 2630 years
E) 2940 years
72) The radioactivity due to carbon-14 measured in a piece of a wooden casket from an ancient
burial site is found to produce 20 counts per minute from a given sample, whereas the same
amount of carbon from a piece of living wood produces 160 counts per minute. The half-life of
carbon-14, a beta-minus emitter, is 5730 years. What would we calculate for the age of the
artifact, assuming that the activity for living wood has remained constant over time?
A) 5,700 years
B) 11,500 years
C) 14,800 years
D) 17,200 years
E) 23,000 years
73) The maximum permissible workday dose for occupational exposure to radiation is 18 mrem.
A 54-kg laboratory technician absorbs 2.6 mJ of 0.30-MeV gamma rays in a work day. The
relative biological effectiveness (RBE) for gamma rays is 1.00. What is the ratio of the
equivalent dosage received by the technician to the maximum permissible equivalent dosage?
A) 0.27
B) 0.29
C) 0.32
D) 0.35
E) 0.37
35
74) The maximum permissible workday dose for occupational exposure to radiation is 11 mrem.
A 77-kg laboratory technician absorbs 2.3 mJ of 0.5-MeV gamma rays in a work day. The
relative biological effectiveness (RBE) for gamma rays is 1.00. What is the number of gamma-
ray photons absorbed by the technician in a workday?
A) 3 × 1010
B) 3 × 109
C) 3 × 108
D) 1 × 109
E) 1 × 108
75) A 70-kg researcher absorbs 4.5 × neutrons in a work day, each of energy 1.2 MeV. The
relative biological effectiveness (RBE) for these neutrons is 10. What is the equivalent dosage of
the radiation exposure for this researcher, in millirem?
A) 1.2 mrem
B) 0.39 mrem
C) 0.77 mrem
D) 3.7 mrem
E) 12 mrem
76) Determine the missing product X in the nuclear reaction U + n → X + 2β–.
77) Determine the missing product X in the following nuclear reaction:
O + neutron → X + alpha particle
78) Determine the missing product X in the following nuclear reaction:
U + neutron → Ba + X + 3 neutrons
36
79) Determine the missing product X in the following nuclear reaction:
B + neutron → X + alpha particle
80) Determine the missing product X in the following nuclear reaction:
N + neutron → X + alpha particle
81) The equation shows a fission reaction:
U + n → Nb + X + 4 n
What is the missing term X in the equation?
A) Ag
B) Sb
C) Sb
D) Ag
E) Sb
82) In the fission reaction 235U + 1n → 141Ba + 92Kr + x 1n, what is the number x of neutrons
produced?
A) 0
B) 1
C) 2
D) 3
37
83) In the nuclear reaction O + He → X + Ne, what is X?
A) proton
B) neutron
C) 2H
D) 3H
E) alpha particle
84) In the nuclear reaction O + n → X + He, what is X?
A) 12C
B) 13C
C) 14C
D) 15C
E) 17O
85) In the nuclear reaction K + H → X + Ca, what is X?
A) proton
B) neutron
C) 2H
D) 3H
E) alpha particle
86) In the nuclear reaction H + H → X + He, what is X?
A) 2 protons
B) 2 neutrons
C) 2H
D) 3H
E) alpha particle
87) A proton strikes an oxygen-18 nucleus, producing fluorine-18 and another particle X. What
is the other particle X?
A) neutron
B) positron
C) alpha particle
D) electron
E) gamma ray
88) A hypothetical particle has a mass of 510 MeV/c2. If such a particle at rest decays into two
gamma-ray photons, what is the wavelength of each photon? (1 eV = 1.60 × 10-19 J, c = 3.00 ×
108 m/s, h = 6.626 × 10-34 J∙ s)
89) If a Σ– particle at rest decays into a neutron and a π– , what is the total kinetic energy of the
decay products? The masses of Σ–, neutron, and π– are 1197 MeV/c2, 940 MeV/c2, and 140
MeV/c2, respectively.
90) Consider the fusion reaction:
H + H + H → He + H + n
The know atomic masses are
H: 2.01410 u
He: 4.00260 u
H: 1.00783 u
n: 1.008665 u
where 1 u = 1.6605 × 10-27 kg. What mass of deuterium fuel, H, is used up in producing
of energy by this reaction?
39
91) Consider the nuclear reaction N + He → O + H. The known atomic masses are
N: 14.003074 u
He: 4.002603 u
H: 1.007825 u
O: 16.999131 u
What is the Q-value (or reaction energy) of this reaction? (1 u = 931.5 MeV/c2)
A) -1.191 MeV
B) -2.020 MeV
C) -6.725 MeV
D) -9.055 MeV
92) Consider the nuclear reaction: 7Li + 1p → 4He + 4He. The known atomic masses are
7Li: 7.016005 u
He: 4.002603 u
1p: 1.007825 u
What is the Q-value (or reaction energy) of this reaction? (1 u = 931.5 MeV/c2)
A) 13.57 MeV
B) 15.37 MeV
C) 17.35 MeV
D) 17.53 MeV
40
93) Consider the nuclear reaction N + He → O + H. The known atomic masses are
N: 14.003074 u
He: 4.002603 u
H: 1.007825 u
O: 16.999131 u
What is the Q-value (or reaction energy) of this reaction? (1 u = 931.5 MeV/c2)
A) 1.191 MeV
B) -1.191 MeV
C) 1.279 × 10-3 MeV
D) -1.279 × 10-3 MeV
94) Consider the nuclear reaction H + H → He + 2 n. The known atomic masses are
He: 4.002603 u
H: 3.016049u
n: 1.008665 u
What is the energy released (positive) or absorbed (negative) in this nuclear reaction? (1 u =
931.5 MeV/c2)
A) 0.0122 MeV
B) -0.0122 MeV
C) 11.3 MeV
D) -11.3 MeV
95) A nuclear explosion results in a mass decrease of How much energy is released during
this explosion? (c = 3.00 × 108 m/s)
A) 1.89 × 1014 J
B) 6.30 × 105 J
C) 1.89 × 1013 J
D) 2.25 × 1012 J
96) An electron and a positron, both essentially at rest, annihilate each other, emitting two
identical photons in the process. What is the wavelength of these photons? The mass of an
electron or positron is 9.11 × 10-31 kg. (h = 6.626 × 10-34 J ∙ s, c = 3.00 × 108 m/s)
A) 1.21 × 10-12 pm
B) 1.73 pm
C) 2.42 pm
D) 3.07 pm
E) 3.46 pm
97) An excited U* nucleus undergoes fission into two fragments as follows:
U*→ Ba + Kr
The following atomic masses are known:
Kr: 91.926270 u
Ba: 143.922845 u
U*: 236.045563 u
What is the reaction energy released during this fission reaction? (1 u = 931.5 MeV/c2)
A) 150 MeV
B) 160 MeV
C) 170 MeV
D) 180 MeV
E) 190 MeV
98) When a neutron collides with a uranium-235 nucleus it can induce a variety of fission
reactions. One such reaction is
U + n → Xe + Sr + 2 n
The following mass values are known:
Xe: 139.921620 u
Sr: 93.915367 u
U: 235.043924 u
n: 1.008665 u
How much energy is released in this reaction? (1 u = 931.5 MeV/c2)
A) 185 MeV
B) 202 MeV
C) 32.6 MeV
D) 65.7 MeV
E) 98.6 MeV
99) When a neutron collides with a uranium-235 nucleus it can induce a variety of fission
reactions. One such reaction is
U + n → Xe + Sr + 2 n
The following mass values are known:
Xe: 139.921620 u
Sr: 93.915367 u
U: 235.043924 u
n: 1.008665 u
What mass of uranium is needed to produce a 10-kiloton yield? (1 u = 931.5 MeV/c2 = 1.66054
× 10-27 kg, 1-kiloton yield = 5.0 × 1012 J)
A) 0.57 kg
B) 0.66 kg
C) 6.58 kg
D) 3.85 kg
E) 1.10 kg
100) Two deuterium nuclei, H, fuse to produce a tritium nucleus, H, plus an ordinary
hydrogen nucleus, H. A neutral deuterium atom has a mass of 2.014102 u; a neutral tritium
atom has a mass of 3.016050 u; a neutral hydrogen atom has a mass of 1.007825 u; a neutron has
a mass of 1.008665 u; and a proton has a mass of 1.007277 u. How much energy is released in
this fusion process? (1 u = 931.5 MeV/c2)
A) 3.03 MeV
B) 3.53 MeV
C) 4.03 MeV
D) 4.53 MeV
E) 6.58 MeV
101) If a 2.0-MeV neutron released in a fission reaction loses half its kinetic energy in each
moderator collision, how many collisions are needed to reduce its kinetic energy to 1/25 eV?
A) 6
B) 18
C) 26
D) 30
E) 4
102) If a nuclear fission reactor produces an average power of 1.0 GW over the course of a year,
what mass of 235U is used up for a 365-day year if 200 MeV are released per fission reaction? (1
eV = 1.60 × 10-19 J, mneutron ≈ mproton = 1.67 × 10-27 kg)
A) 0.35 kg
B) 1.75 kg
C) 390 kg
D) 1.1 × 108 kg
E) 3.3 × 108 kg
103) When 235U undergoes fission, the average energy per fission event is 200 MeV. How
much energy is released in the total fission of of (1 eV = 1.60 × 10-19 J, mneutron ≈
mproton = 1.67 × 10-27 kg)
A) 1.6 × 1011 J
B) 3.9 × 1013 J
C) 1.6 × 105 J
D) 3.9 × 1010 J