6) When an atom of an element undergoes beta decay, its proton count will change by ________ and its
neutron count will change by ________.
A) +1, -1
B) 0, 0
C) -1, +1
D) -2, -2
E) -1, -1
7) What is the missing product from this reaction?
Ca → Sc + ____
A) e
B) γ
C) e
D) He
E) Ca
8) What is the missing product from this reaction?
Cm → _____ + He
A) Pu
B) U
C) Cf
D) Fm
E) Cm
9) What is the missing product from this reaction?
Tl → _____ + e
A) Pb
B) Hg
C) Tl
D) Tl
E) Tl
10) What is the missing product from this reaction?
Na → _____ + e
A) Ne
B) Mg
C) Na
D) Na
E) Na
11) The product of the nuclear reaction in which 40Ar is subjected to neutron capture followed by alpha
emission is ________.
A) 37S
B) 41Ar
C) 36S
D) 45Ca
E) 35Ar
12) The half-life of cobalt-60 is 5.20 yr. How many milligrams of a 2.000-mg sample remain after 9.50
years?
A) 0.565
B) 7.03 × 10–22
C) 7.076
D) 1.095
E) 1.435
13) Strontium-90 is a byproduct in nuclear reactors fueled by the radioisotope uranium-235. The half-life
of strontium-90 is 28.8 yr. What percentage of a strontium-90 sample remains after 175.0 yr?
A) 84.8
B) 1.48
C) 0.230
D) 16.5
E) 6.08
14) Carbon-11 is used in medical imaging. The half-life of this radioisotope is 20.4 min. What percentage
of a sample remains after 50.0 min?
A) 66.5
B) 8.62
C) 18.3
D) 40.8
E) 2.45
15) A rock contains 0.153 mg of lead-206 for each milligram of uranium-238. The half-life for the decay of
uranium-238 to lead-206 is 4.5 × 109 yr. The rock was formed ________ years ago.
A) 6.89 × 108
B) 5.60 × 108
C) 7.33 × 108
D) 1.06 × 109
E) 8.08 × 108
16) 131I has a half-life of 8.04 days. Assuming you start with a 1.03 mg sample of 131I, how many mg will
remain after 13.0 days?
A) 0.326
B) 0.268
C) 0.422
D) 0.0781
E) 0.336
17) The decay of a radionuclide with a half-life of 3.3 × 105 years has a rate constant (in yr-1) equal to
________.
A) 4.8 × 105
B) 2.1 × 10-6
C) 4.2 × 10-6
D) 2.8 × 103
E) 5.9 × 10-8
18) Potassium-40 decays to argon-40 with a half-life of 1.27 × 109 yr. The age of a mineral sample that has
a mass ratio of 40Ar to 40K of 0.330 is ________ yr.
A) 3.85 × 109
B) 1.77 × 109
C) 2.55 × 109
D) 3.62 × 108
E) 5.23 × 108
19) If we start with 1.000 g of strontium-90, 0.805 g will remain after 9.00 yr. This means that the half-life
of strontium-90 is ________ yr.
A) 7.74
B) 11.2
C) 28.8
D) 7.25
E) 41.6
41
20) If we start with 1.000 g of cobalt-60, 0.400 g will remain after 7.00 yr. This means that the half-life of
cobalt-60 is ________ yr.
A) 12.1
B) 17.5
C) 2.80
D) 5.30
E) 7.65
21) A freshly prepared sample of curium-243 undergoes 3312 disintegrations per second. After 8.00 yr,
the activity of the sample declines to 2591 disintegrations per second. The half-life of curium-243 is
A) 6.26
B) 32.6
C) 10.2
D) 1.36
E) 22.6
22) The beta decay of cesium-137 has a half-life of 30.0 years. How many years must pass to reduce a 30
mg sample of cesium 137 to 5.2 mg?
A) 76 years
B) -76 years
C) 38 years
D) 0.040 years
E) 25 years
23) The half-life of 218Po is 3.1 minutes. How much of a 170 gram sample remains after 0.64 hours?
A) 0.032 g
B) 150 g
C) 31 g
D) 4.7 × 10–10 g
E) None of the original sample will remain.
24) Cesium-131 has a half-life of 9.7 days. What percent of a cesium-131 sample remains after 62 days?
A) 1.2 %
B) 100 %
C) 0 %
D) 99 %
E) 62%
25) The half-life of carbon-11 is 20.3 minutes. How much of a 100.0 mg sample remains after 1.6 hours?
A) 3.77 mg
B) 0.0377 mg
C) 94.7 mg
D) 1.75 × 10–89 mg
E) 99.9 mg
26) 210Pb has a half-life of 22.3 years and decays to produce 206Hg. If you start with 7.52 g of 210Pb, how
many grams of 206Hg will you have after 15.8 years?
A) 4.60 g
B) 2.83 g
C) 9.20 g
D) 2.30 g
E) 12.5 g
27) Carbon-11 decays by positron emission:
C → B + e
The decay occurs with a release of 2.87 × 1011 J per mole of carbon-11. When 5.00 g of carbon-11
undergoes this radioactive decay, ________ g of mass is converted to energy.
A) 1.45 × 10-3
B) 4.35 × 105
C) 1.45 × 10-6
D) 6.90 × 102
E) 1.59 × 10-2
28) How much energy (in J) is produced when 0.067 g of matter is converted to energy?
A) 6.0 × 1018
B) 6.0 × 1012
C) 2.0 × 104
D) 6.0 × 1015
E) 2.0 × 107
29) The mass of a proton is 1.673 × 10-24 g. The mass of a neutron is 1.675 × 10–24 g. The mass of the
nucleus of an 59Fe atom is 9.787 × 10–23 g. What is the nuclear binding energy (in J) for a 59Fe nucleus?
(c = 3.00 × 108 m/s)
A) 8.13 × 10–11 J
B) 2.71 × 10–19 J
C) 8.13 × 10-8 J
D) 4.00 × 10-9 J
E) -9.74 × 10–10 J
30) The mass of a proton is 1.00728 amu and that of a neutron is 1.00867 amu. What is the binding energy
(in J) of a 62Co nucleus? (The mass of a cobalt-62 nucleus is 61.9341 amu.)
A) 8.46 × 10–11 J
B) 8.46 × 10–19 J
C) 5.09 × 1016 J
D) 4.15 × 10-9 J
E) -1.12 × 10-9 J
31) The mass of a proton is 1.00728 amu and that of a neutron is 1.00867 amu. What is the binding energy
per nucleon (in J) of a 59Co nucleus? (The mass of a cobalt-59 nucleus is 58.9332 amu.)
A) 4.87 × 1010 J
B) 4.87 × 1013 J
C) 1.34 × 10–34 J
D) 2.50 × 1012 J
E) 4.80 × 1010 J
32) The mass of a proton is 1.00728 amu and that of a neutron is 1.00867 amu. What is the mass defect (in
amu) of a 57Ni nucleus? (The mass of a nickel-60 nucleus is 59.9308 amu.)
A) 0.5155 amu
B) 28.76 amu
C) -0.4932 amu
D) 0.5141 amu
E) 1.031 amu
21.4 Short Answer Questions
1) What happens in the nucleus of an atom that undergoes positron emission?
2) What is the predominant isotope of uranium?
3) What happens to the atomic mass number and the atomic number of a radioisotope when it undergoes
alpha emission?
4) High speed electrons emitted by an unstable nucleus are called ________.
5) e represents ________.
6) What isotope of what element is produced if krypton-81 undergoes beta decay?
7) Stable nuclei with low atomic numbers, up to 20, have a neutron to proton ratio of approximately
________.
8) The first nuclear transmutation resulted in the conversion of nitrogen-14 to ________.
9) Conversion of one nucleus into another was first demonstrated in 1919 by ________.
10) The initial element used to make cobalt-60 for cancer radiation therapy is ________.
11) The half-life for the beta decay of potassium-40 is 1.3 × 109 years. What is the rate constant for this
decay?
12) ________ discovered radioactivity.
13) Carbon-11, fluorine-18, oxygen-15 and nitrogen-13 are all used in the clinical diagnostic technique
known as ________.
14) What is the source of the tremendous energies produced by nuclear reactions?
15) Control rods in a nuclear reactor are composed of boron and ________.
16) The amount of fissionable material necessary to maintain a chain reactions is called the ________.
17) What was the purpose of the Manhattan project?
18) When living tissue is irradiated most of the energy is absorbed by ________.
19) The relative biological effectiveness (RBE) values of beta rays, gamma rays, and alpha rays are
________, respectively.
20) The major type of cancer caused by radiation is ________.
21) Radioactive seeds that are implanted into a tumor are coated with ________ to stop alpha and beta ray
penetration.
21.5 True/False Questions
1) Gamma radiation only changes the atomic number but not the mass number of a nucleus.
2) Positron emission causes a decrease of one in the atomic number.
3) The neutron/proton ratio of stable nuclei increases with increasing atomic number.
4) Charged particles are accelerated because the faster they move there is a greater chance of producing a
nuclear reaction.
5) Radioactive decay is a first order kinetic process.
6) In radioactive dating, the ratio of carbon-12 to carbon-14 is related to the time of death of the animal or
plant under investigation.
7) In the formula k = 0.693/t1/2, k is the decay constant.
8) The energy produced by the sun is the result of nuclear fusion.
9) The SI unit of an absorbed dose of radiation is the gray.
10) The relative biological effectiveness (RBE) is tenfold greater for gamma radiation than for alpha
radiation.
1) Electrons do not exist in the nucleus, yet beta emission is ejection of electrons from the nucleus. How
does this happen?
2) List the common particles and their symbols used in descriptions of radioactive decay and nuclear
transformations.
3) When an isotope undergoes electron capture, what happens to the captured electron?
4) The use of radioisotopes in tracing metabolism is possible because ________.