Question 1

Scandium,   Sc, decays by emitting a positron. What is the nuclide that is the product of the decay?

Accepted Answer

A)    Sc 
B)    Sc 
C)    Ca 
D)    Ca 
E)    Sc 
A)    Sc 
B)    Sc 
C)    Ca 
D)    Ca 
E)    Sc

Question 2

Two identical nuclei of mass 18 u are made to unite to make a single nucleus of mass 36 u. What is the radius of the result of this fusion?

Accepted Answer

A)  4.0 fm 
B)  6.3 fm 
C)  4.5 fm 
D)  7.2 fm 
A)  4.0 fm 
B)  6.3 fm 
C)  4.5 fm 
D)  7.2 fm

Question 3

The neutral deuterium atom,   H, has a mass of 2.014102 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. What is the binding energy of the  
H nucleus? (1 u = 931.494 MeV/c2)

Accepted Answer

A)  1.1 MeV 
B)  1.7 MeV 
C)  2.2 MeV 
D)  2.9 MeV 
E)  3.4 MeV 
A)  1.1 MeV 
B)  1.7 MeV 
C)  2.2 MeV 
D)  2.9 MeV 
E)  3.4 MeV

Question 4

Uranium-238 decays into thorium-234 plus an alpha particle. How much energy is released in this process? 1 u = 931.494 MeV/c2, and the relevant mass values are   He: 4.002603 u  
Th: 234.043583 u  
U: 238.050786 u

Accepted Answer

A)  4.28 MeV 
B)  3.76 MeV 
C)  3.18 MeV 
D)  2.89 MeV 
E)  5.05 MeV 
A)  4.28 MeV 
B)  3.76 MeV 
C)  3.18 MeV 
D)  2.89 MeV 
E)  5.05 MeV

Question 5

If a nucleus decays by β+ decay to a daughter nucleus, which of the following statements about this decay are correct? (There may be more than one correct choice.)

Accepted Answer

A)  The daughter nucleus has more protons than the original nucleus. 
B)  The daughter nucleus has more neutrons than the original nucleus. 
C)  The daughter nucleus has the same number of nucleons as the original nucleus. 
D)  The daughter nucleus has fewer protons than the original nucleus. 
E)  The daughter nucleus has fewer neutrons than the original nucleus. 
A)  The daughter nucleus has more protons than the original nucleus. 
B)  The daughter nucleus has more neutrons than the original nucleus. 
C)  The daughter nucleus has the same number of nucleons as the original nucleus. 
D)  The daughter nucleus has fewer protons than the original nucleus. 
E)  The daughter nucleus has fewer neutrons than the original nucleus.

Question 6

The radioactivity due to carbon-14 measured in a piece of a wood from an ancient site was found to produce 20 counts per minute from a given sample, whereas the same amount of carbon from a piece of living wood produced 160 counts per minute. The half-life of carbon-14, a beta emitter, is 5730 y. The age of the artifact is closest to

Accepted Answer

A)  5700 y 
B)  12,000 y 
C)  15,000 y 
D)  17,000 y 
E)  23,000 y 
A)  5700 y 
B)  12,000 y 
C)  15,000 y 
D)  17,000 y 
E)  23,000 y

Question 7

The material used in certain nuclear bombs is 239Pu, which has a half-life of about 20,000 years. How long must we wait for a buried stockpile of this substance to decay to 4.0% of its original 239Pu mass?

Accepted Answer

A)  93,000 y 
B)  64,000 y 
C)  45,000 y 
D)  800 y 
A)  93,000 y 
B)  64,000 y 
C)  45,000 y 
D)  800 y

Question 8

What mass of 14C (having a half-life of 5730 years) do you need to provide a decay rate of
280.0 Bq? (1 u = 1.6605 × 10-27 kg)

Accepted Answer

A)  1.70 × 10-12 kg 
B)  5.38 × 10-19 kg 
C)  3.84 × 10-20 kg 
D)  8.68 × 10-13 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

Question 9

A certain substance has a half-life of 5.0 hours. How many nuclei of the substance are required to give an initial activity of 6.0 μCi? 1 Ci = 3.7 × 1010 Bq.

Accepted Answer

A)  5.8 × 109 
B)  8.5 × 108 
C)  6.3 × 108 
D)  3.2 × 109 
E)  2.4 × 109 
A)  5.8 × 109 
B)  8.5 × 108 
C)  6.3 × 108 
D)  3.2 × 109 
E)  2.4 × 109

Question 10

The stability of   Sc with respect to alpha, β+, and β- decay is to be determined. Do not consider the possibility of decay by electron capture. The following atomic masses are known:  
He: 4.002603 u  
K: 42.960717 u  
Ca: 46.954543 u  
Sc 46.952409 u  
Ti: 46.951764 u
The  
Sc nuclide is

Accepted Answer

A)  not subject to alpha, β+, or β- decay. 
B)  subject to alpha decay only. 
C)  subject to β+ decay only. 
D)  subject to β- decay only. 
E)  subject to β+ or β- decay, but not to alpha decay. 
A)  not subject to alpha, β+, or β- decay. 
B)  subject to alpha decay only. 
C)  subject to β+ decay only. 
D)  subject to β- decay only. 
E)  subject to β+ or β- decay, but not to alpha decay.

Question 11

An isotope of Tc having a half-life of 6.0 h is used in bone scans. If a certain amount of this Tc is injected into the body, how long does it take for its initial decay rate to decrease BY 99%?

Accepted Answer

A)  "0.060 h" 
B)  "3.3 h" 
C)  "33 h" 
D)  "40 h" 
E)  "slightly more than a month" 
A)  "0.060 h" 
B)  "3.3 h" 
C)  "33 h" 
D)  "40 h" 
E)  "slightly more than a month"

Question 12

Heavier stable nuclei tend to have

Accepted Answer

A)  half as many protons as neutrons. 
B)  the same number of neutrons and protons. 
C)  more neutrons than protons. 
D)  no clear trend in the relative number of neutrons and protons. 
E)  more protons than neutrons. 
A)  half as many protons as neutrons. 
B)  the same number of neutrons and protons. 
C)  more neutrons than protons. 
D)  no clear trend in the relative number of neutrons and protons. 
E)  more protons than neutrons.

Question 13

A radioactive nuclide of atomic number Z emits an electron, then the daughter nuclide emits a gamma ray. What is the atomic number of the resulting nuclide after both processes?

Accepted Answer

A)  Z + 1 
B)  Z - 1 
C)  Z - 2 
D)  Z - 3 
E)  Z + 2 
A)  Z + 1 
B)  Z - 1 
C)  Z - 2 
D)  Z - 3 
E)  Z + 2

Question 14

For a   Nb atom, the number of protons, neutrons, and electrons in the atom is

Accepted Answer

A)  41, 52, 93. 
B)  41, 52, 52. 
C)  41, 52, 41. 
D)  41, 52, 0. 
E)  52, 41, 0. 
A)  41, 52, 93. 
B)  41, 52, 52. 
C)  41, 52, 41. 
D)  41, 52, 0. 
E)  52, 41, 0.

Question 15

The half-life of cobalt-60 is 5.3 years, while that of strontium-90 is 28 years. Suppose that samples of cobalt-60 and strontium-90 are such that they initially have the same activity (number of decays per second). What is true about the initial numbers of cobalt-60 and strontium-90 nuclei in these samples?

Accepted Answer

A)  There are more strontium-90 than cobalt-60 nuclei. 
B)  There are equal numbers of cobalt-60 and strontium-90 nuclei. 
C)  There are more cobalt-60 than strontium-90 nuclei. 
D)  It is not possible to compare numbers of nuclei without knowing the masses of the samples. 
A)  There are more strontium-90 than cobalt-60 nuclei. 
B)  There are equal numbers of cobalt-60 and strontium-90 nuclei. 
C)  There are more cobalt-60 than strontium-90 nuclei. 
D)  It is not possible to compare numbers of nuclei without knowing the masses of the samples.

Question 16

What would be the expected radius of the nucleus of   Sr?

Accepted Answer

A)  4.0 fm 
B)  1.2 fm 
C)  5.4 fm 
D)  0.11 pm 
E)  0.54 pm 
A)  4.0 fm 
B)  1.2 fm 
C)  5.4 fm 
D)  0.11 pm 
E)  0.54 pm

Question 17

If a nucleus decays by alpha decay to a daughter nucleus, which of the following statements about this decay are correct? (There may be more than one correct choice.)

Accepted Answer

A)  The daughter nucleus has more protons than the original nucleus. 
B)  The daughter nucleus has more neutrons than the original nucleus. 
C)  The daughter nucleus has the same number of nucleons as the original nucleus. 
D)  The daughter nucleus has fewer protons than the original nucleus. 
E)  The daughter nucleus has fewer neutrons than the original nucleus. 
A)  The daughter nucleus has more protons than the original nucleus. 
B)  The daughter nucleus has more neutrons than the original nucleus. 
C)  The daughter nucleus has the same number of nucleons as the original nucleus. 
D)  The daughter nucleus has fewer protons than the original nucleus. 
E)  The daughter nucleus has fewer neutrons than the original nucleus.

Question 18

A 57-kg researcher absorbs 6.3 × 108 neutrons in a workday. The energy of the neutrons is 2.6 MeV. The relative biological efficiency (RBE) for fast neutrons is 10. What is the equivalent dosage of the radiation exposure, in mrem, of this worker?

Accepted Answer

A)  4.6 mrem 
B)  1.4 mrem 
C)  2.9 mrem 
D)  14 mrem 
E)  46 mrem 
A)  4.6 mrem 
B)  1.4 mrem 
C)  2.9 mrem 
D)  14 mrem 
E)  46 mrem

Question 19

The set of nuclear reactions that power our sun can be summarized a 4p+ → 4He+2 + 2e+. The masses of the particles involved are 938.272 MeV/c2 (proton, p+), 3727.38 MeV/c2 (alpha particle, 4He+2), and 0.511 MeV/c2 (positron, e+). How much energy is released by each set of these reactions?

Accepted Answer

A)  24.69 MeV 
B)  28.3 MeV 
C)  2790 MeV 
D)  279 MeV 
A)  24.69 MeV 
B)  28.3 MeV 
C)  2790 MeV 
D)  279 MeV

Question 20

Fermium-253 has a half-life of 3.00 d. A sample of fermium contains 7.37 × 107 nuclei. How long will it take for there to be only 3.36 × 106 fermium nuclei in this sample?

Accepted Answer

A)  2.75 d 
B)  9.80 d 
C)  13.4 d 
D)  15.7 d 
E)  58.6 d 
A)  2.75 d 
B)  9.80 d 
C)  13.4 d 
D)  15.7 d 
E)  58.6 d

Exam 42: Nuclear Physics

Scandium, Sc, decays by emitting a positron. What is the nuclide that is the product of the decay?

Two identical nuclei of mass 18 u are made to unite to make a single nucleus of mass 36 u. What is the radius of the result of this fusion?

The neutral deuterium atom, H, has a mass of 2.014102 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. What is the binding energy of the H nucleus? (1 u = 931.494 MeV/c2)

Uranium-238 decays into thorium-234 plus an alpha particle. How much energy is released in this process? 1 u = 931.494 MeV/c2, and the relevant mass values are He: 4.002603 u Th: 234.043583 u U: 238.050786 u

If a nucleus decays by β+ decay to a daughter nucleus, which of the following statements about this decay are correct? (There may be more than one correct choice.)

The material used in certain nuclear bombs is 239Pu, which has a half-life of about 20,000 years. How long must we wait for a buried stockpile of this substance to decay to 4.0% of its original 239Pu mass?

What mass of 14C (having a half-life of 5730 years) do you need to provide a decay rate of 280.0 Bq? (1 u = 1.6605 × 10-27 kg)

A certain substance has a half-life of 5.0 hours. How many nuclei of the substance are required to give an initial activity of 6.0 μCi? 1 Ci = 3.7 × 1010 Bq.

The stability of Sc with respect to alpha, β+, and β- decay is to be determined. Do not consider the possibility of decay by electron capture. The following atomic masses are known: He: 4.002603 u K: 42.960717 u Ca: 46.954543 u Sc 46.952409 u Ti: 46.951764 u The Sc nuclide is

An isotope of Tc having a half-life of 6.0 h is used in bone scans. If a certain amount of this Tc is injected into the body, how long does it take for its initial decay rate to decrease BY 99%?

Heavier stable nuclei tend to have

A radioactive nuclide of atomic number Z emits an electron, then the daughter nuclide emits a gamma ray. What is the atomic number of the resulting nuclide after both processes?

For a Nb atom, the number of protons, neutrons, and electrons in the atom is

What would be the expected radius of the nucleus of Sr?

If a nucleus decays by alpha decay to a daughter nucleus, which of the following statements about this decay are correct? (There may be more than one correct choice.)

A 57-kg researcher absorbs 6.3 × 108 neutrons in a workday. The energy of the neutrons is 2.6 MeV. The relative biological efficiency (RBE) for fast neutrons is 10. What is the equivalent dosage of the radiation exposure, in mrem, of this worker?

The set of nuclear reactions that power our sun can be summarized a 4p+ → 4He+2 + 2e+. The masses of the particles involved are 938.272 MeV/c2 (proton, p+), 3727.38 MeV/c2 (alpha particle, 4He+2), and 0.511 MeV/c2 (positron, e+). How much energy is released by each set of these reactions?

Fermium-253 has a half-life of 3.00 d. A sample of fermium contains 7.37 × 107 nuclei. How long will it take for there to be only 3.36 × 106 fermium nuclei in this sample?

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The neutral deuterium atom, H, has a mass of 2.014102 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. What is the binding energy of the H nucleus? (1 u = 931.494 MeV/c²)

Uranium-238 decays into thorium-234 plus an alpha particle. How much energy is released in this process? 1 u = 931.494 MeV/c², and the relevant mass values are He: 4.002603 u Th: 234.043583 u U: 238.050786 u

If a nucleus decays by β⁺ decay to a daughter nucleus, which of the following statements about this decay are correct? (There may be more than one correct choice.)

The material used in certain nuclear bombs is ²³⁹Pu, which has a half-life of about 20,000 years. How long must we wait for a buried stockpile of this substance to decay to 4.0% of its original ²³⁹Pu mass?

What mass of ¹⁴C (having a half-life of 5730 years) do you need to provide a decay rate of 280.0 Bq? (1 u = 1.6605 × 10^-27 kg)

A certain substance has a half-life of 5.0 hours. How many nuclei of the substance are required to give an initial activity of 6.0 μCi? 1 Ci = 3.7 × 10¹⁰ Bq.

The stability of Sc with respect to alpha, β⁺, and β^- decay is to be determined. Do not consider the possibility of decay by electron capture. The following atomic masses are known: He: 4.002603 u K: 42.960717 u Ca: 46.954543 u Sc 46.952409 u Ti: 46.951764 u The Sc nuclide is

_{An isotope of Tc having a half-life of 6.0 h is used in bone scans. If a certain amount of this Tc is injected into the body, how long does it take for its initial decay rate to decrease BY 99%?}

A 57-kg researcher absorbs 6.3 × 10⁸ neutrons in a workday. The energy of the neutrons is 2.6 MeV. The relative biological efficiency (RBE) for fast neutrons is 10. What is the equivalent dosage of the radiation exposure, in mrem, of this worker?

Fermium-253 has a half-life of 3.00 d. A sample of fermium contains 7.37 × 10⁷ nuclei. How long will it take for there to be only 3.36 × 10⁶ fermium nuclei in this sample?