Question 1

A thermal neutron has an energy (in eV) on the order of

Accepted Answer

A)  40 
B)  0.4 
C)  4 
D)  0.04 
E)  400 
A)  40 
B)  0.4 
C)  4 
D)  0.04 
E)  400

Question 2

For large mass number nuclei which are stable, the ratio of protons to neutrons is

Accepted Answer

A)  equal to 1 
B)  greater than 1 
C)  less than 1 
D)  unrelated to the stability of nuclei 
E)  almost 2 to 1 
A)  equal to 1 
B)  greater than 1 
C)  less than 1 
D)  unrelated to the stability of nuclei 
E)  almost 2 to 1

Question 3

Linus claims that the added gravitational force of neutrons holds the particles in a nucleus together. Linnea says that they stick together because they lose their electric charge when they form a nucleus. Which one, if either, is correct, and why?

Accepted Answer

A)  Linus, because more particles exert gravitational forces on one another than exert electromagnetic forces. 
B)  Linus, because the numerical magnitude of G/ke is 7.42 × 10−21. 
C)  Linnea, because the numerical magnitude of G/ke is 7.42 × 10−21. 
D)  Both, because electric charge is lost and then gravity holds the nucleus together. 
E)  Neither, because gravity is not lost, and the numerical magnitude of ke/G is 1.35 × 1020. 
A)  Linus, because more particles exert gravitational forces on one another than exert electromagnetic forces. 
B)  Linus, because the numerical magnitude of G/ke is 7.42 × 10−21. 
C)  Linnea, because the numerical magnitude of G/ke is 7.42 × 10−21. 
D)  Both, because electric charge is lost and then gravity holds the nucleus together. 
E)  Neither, because gravity is not lost, and the numerical magnitude of ke/G is 1.35 × 1020.

Question 4

In order to control a nuclear reactor, control rods can be pulled out of or pushed into the reactor core by remote control. These rods control the reactor by

Accepted Answer

A)  slowing down the fast neutrons so the neutrons can be absorbed by 238U. 
B)  speeding up slow neutrons so the neutrons can be absorbed by 238U. 
C)  slowing down fast neutrons so they cannot initiate further fusion reactions in 235U. 
D)  speeding up fast neutrons so they cannot initiate further fusion reactions in 235U. 
E)  capturing thermal neutrons so they cannot initiate further fission reactions in 235U. 
A)  slowing down the fast neutrons so the neutrons can be absorbed by 238U. 
B)  speeding up slow neutrons so the neutrons can be absorbed by 238U. 
C)  slowing down fast neutrons so they cannot initiate further fusion reactions in 235U. 
D)  speeding up fast neutrons so they cannot initiate further fusion reactions in 235U. 
E)  capturing thermal neutrons so they cannot initiate further fission reactions in 235U.

Question 5

The chart below shows part of the radioactive series beginning with the isotope   . The isotope marked with an X is

Accepted Answer

A) 
  . 
B) 
  . 
C) 
  . 
D) 
  . 
E) 
  . 
A) 
  . 
B) 
  . 
C) 
  . 
D) 
  . 
E) 
  .

Question 6

The reaction energy associated with a nuclear reaction is

Accepted Answer

A)  the total change in rest energy as a result of the reaction. 
B)  equivalent to the disintegration energy. 
C)  the minimum energy necessary for such a reaction to occur. 
D)  called the threshold energy. 
E)  the binding energy of the nucleons. 
A)  the total change in rest energy as a result of the reaction. 
B)  equivalent to the disintegration energy. 
C)  the minimum energy necessary for such a reaction to occur. 
D)  called the threshold energy. 
E)  the binding energy of the nucleons.

Question 7

The isotope, tritium, has a half-life of 12.3 years. Assume we have 10 kg of the substance. What will be the initial decay rate, at t = 0 (in decays/s)?

Accepted Answer

A)  1.09 × 1014 
B)  1.8 × 10−9 
C)  5.6 × 108 
D)  3.6 × 1018 
E)  3.6 × 1017 
A)  1.09 × 1014 
B)  1.8 × 10−9 
C)  5.6 × 108 
D)  3.6 × 1018 
E)  3.6 × 1017

Question 8

Find the binding energy (in MeV) of carbon-12. Assume:
MC = 12.000 000 u
M p = 1.007 825 u
M n = 1.008 665 u
U = 1.66 × 10−27 kg

Accepted Answer

A)  14.8 
B)  0.511 
C)  9.11 
D)  92.3 
E)  46.2 
A)  14.8 
B)  0.511 
C)  9.11 
D)  92.3 
E)  46.2

Question 9

Because we know that the half-lives of many radioactive isotopes are millions of years, we can deduce that

Accepted Answer

A)  the longer it exists the more radioactive nuclei Earth produces. 
B)  the sun is the source of all the radioactive nuclei on Earth. 
C)  there must have been many more radioactive nuclei on Earth when life began. 
D)  there must have been far fewer radioactive nuclei on Earth before life began. 
E)  the natural radioactivity of minerals on the Earth was created by the Earth's internal temperature. 
A)  the longer it exists the more radioactive nuclei Earth produces. 
B)  the sun is the source of all the radioactive nuclei on Earth. 
C)  there must have been many more radioactive nuclei on Earth when life began. 
D)  there must have been far fewer radioactive nuclei on Earth before life began. 
E)  the natural radioactivity of minerals on the Earth was created by the Earth's internal temperature.

Question 10

Find the ratio of the binding energy per nucleon for helium (   ) to uranium-238 (   ). Assume:
M p = 1.007 825 u
M n = 1.008 665 u
MHe = 4.002 603 u
MU = 238.050 786 u
U = 1.66 × 10−27 kg

Accepted Answer

A)  1.07 
B)  0.934 
C)  63.7 
D)  1.6 × 10−2 
E)  3.24 
A)  1.07 
B)  0.934 
C)  63.7 
D)  1.6 × 10−2 
E)  3.24

Question 11

Homer says that we can safely use nuclear power because all radioactive nuclei are gone after two half-lives. Marge says that only the decay rate is zero after two half-lives. Which one, if either, is correct, and why?

Accepted Answer

A)  Homer, because half of the nuclei disintegrate in each half-life. 
B)  Marge, because the number of decays per unit time is halved in each half-life. 
C)  Homer, because it's safe to handle radioactive substances after two half-lives. 
D)  Both, because when all nuclei disintegrate the decay rate is also zero. 
E)  Neither, because one quarter of the nuclei are left after two half-lives. 
A)  Homer, because half of the nuclei disintegrate in each half-life. 
B)  Marge, because the number of decays per unit time is halved in each half-life. 
C)  Homer, because it's safe to handle radioactive substances after two half-lives. 
D)  Both, because when all nuclei disintegrate the decay rate is also zero. 
E)  Neither, because one quarter of the nuclei are left after two half-lives.

Question 12

How many grams of U-235 must be fissioned every day to produce 1000 MW of electricity in a nuclear power plant that is 1/3 efficient? [Assume 208 MeV/fission and 1 MeV = 1.6 × 10−13 J]

Accepted Answer

Question 13

What is the disintegration energy (in MeV) associated with this spontaneous decay?   mNd = 143.910 083 u mCe = 139.905 434 u
MHe = 4.002 603 u
1 u = 1.66 × 10−27 kg

Accepted Answer

A)  1.54 
B)  2.37 
C)  1.90 
D)  4.13 
E)  8.21 
A)  1.54 
B)  2.37 
C)  1.90 
D)  4.13 
E)  8.21

Question 14

Find the number of nuclei per unit volume (n = nuclei/cm3) for lead. atomic weight = 202.7
Density = 11.5 g/cm3
Avogadro's number = 6.02 × 1023

Accepted Answer

A)  2.51 × 1022 
B)  3.42 × 1022 
C)  2.93 × 1022 
D)  2.94 × 1023 
E)  2.05 × 1021 
A)  2.51 × 1022 
B)  3.42 × 1022 
C)  2.93 × 1022 
D)  2.94 × 1023 
E)  2.05 × 1021

Question 15

In beta decays

Accepted Answer

A)  a proton changes to a neutron. 
B)  a neutron changes to a proton. 
C)  an electron is present in the nucleus before the decay. 
D)  (a), (b) or (c) may occur. 
E)  only (a) or (b) may occur. 
A)  a proton changes to a neutron. 
B)  a neutron changes to a proton. 
C)  an electron is present in the nucleus before the decay. 
D)  (a), (b) or (c) may occur. 
E)  only (a) or (b) may occur.

Question 16

A nuclear reactor is said to be critical when the average number of neutrons from each fission event that cause(s) another fission event is

Accepted Answer

A)  1. 
D)  any of the above. 
E)  only (b) or (c) above. 
A)  1. 
D)  any of the above. 
E)  only (b) or (c) above.

Question 17

A rem (roentgen equivalent in man) is defined as (the product of)

Accepted Answer

A)  the dose in RBE. 
B)  the dose in roentgen and the RBE factor. 
C)  the dose in rad times the dose in roentgen. 
D)  the dose in rad and the RBE factor. 
E)  the dose in rad and energy of radiation. 
A)  the dose in RBE. 
B)  the dose in roentgen and the RBE factor. 
C)  the dose in rad times the dose in roentgen. 
D)  the dose in rad and the RBE factor. 
E)  the dose in rad and energy of radiation.

Question 18

In which of the following decays does the atomic mass number of the daughter nucleus differ from that of the parent nucleus?

Accepted Answer

A) 
  
B) 
  
C) 
  
D) 
  
E)  Answers (a), (b), and (c) are correct. 
A) 
  
B) 
  
C) 
  
D) 
  
E)  Answers (a), (b), and (c) are correct.

Question 19

According to the shell model, binding energy per nucleon is greater when N or Z is equal to one of the numbers below except for

Accepted Answer

A)  2. 
B)  8. 
C)  13. 
D)  20. 
E)  28. 
A)  2. 
B)  8. 
C)  13. 
D)  20. 
E)  28.

Question 20

A beam of high-energy α-particles is incident upon a person and deposits 0.35 J of energy in 0.80 kg of tissue. What dose in rads and what equivalent dose in rems does the individual receive? [RBE α = 20]

Accepted Answer

The answer of A beam of high-energy α-particles is incident...

Exam 44: Nuclear Structure

A thermal neutron has an energy (in eV) on the order of

For large mass number nuclei which are stable, the ratio of protons to neutrons is

Linus claims that the added gravitational force of neutrons holds the particles in a nucleus together. Linnea says that they stick together because they lose their electric charge when they form a nucleus. Which one, if either, is correct, and why?

In order to control a nuclear reactor, control rods can be pulled out of or pushed into the reactor core by remote control. These rods control the reactor by

The chart below shows part of the radioactive series beginning with the isotope . The isotope marked with an X is

The reaction energy associated with a nuclear reaction is

The isotope, tritium, has a half-life of 12.3 years. Assume we have 10 kg of the substance. What will be the initial decay rate, at t = 0 (in decays/s)?

Find the binding energy (in MeV) of carbon-12. Assume: MC = 12.000 000 u M p = 1.007 825 u M n = 1.008 665 u U = 1.66 × 10−27 kg

Because we know that the half-lives of many radioactive isotopes are millions of years, we can deduce that

Find the ratio of the binding energy per nucleon for helium ( ) to uranium-238 ( ). Assume: M p = 1.007 825 u M n = 1.008 665 u MHe = 4.002 603 u MU = 238.050 786 u U = 1.66 × 10−27 kg

Homer says that we can safely use nuclear power because all radioactive nuclei are gone after two half-lives. Marge says that only the decay rate is zero after two half-lives. Which one, if either, is correct, and why?

How many grams of U-235 must be fissioned every day to produce 1000 MW of electricity in a nuclear power plant that is 1/3 efficient? [Assume 208 MeV/fission and 1 MeV = 1.6 × 10−13 J]

What is the disintegration energy (in MeV) associated with this spontaneous decay? mNd = 143.910 083 u mCe = 139.905 434 u MHe = 4.002 603 u 1 u = 1.66 × 10−27 kg

Find the number of nuclei per unit volume (n = nuclei/cm3) for lead. atomic weight = 202.7 Density = 11.5 g/cm3 Avogadro's number = 6.02 × 1023

In beta decays

A nuclear reactor is said to be critical when the average number of neutrons from each fission event that cause(s) another fission event is

A rem (roentgen equivalent in man) is defined as (the product of)

In which of the following decays does the atomic mass number of the daughter nucleus differ from that of the parent nucleus?

According to the shell model, binding energy per nucleon is greater when N or Z is equal to one of the numbers below except for

A beam of high-energy α-particles is incident upon a person and deposits 0.35 J of energy in 0.80 kg of tissue. What dose in rads and what equivalent dose in rems does the individual receive? [RBE α = 20]

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Find the binding energy (in MeV) of carbon-12. Assume: M_C = 12.000 000 u M _p = 1.007 825 u M _n = 1.008 665 u U = 1.66 × 10−²⁷ kg

Find the ratio of the binding energy per nucleon for helium ( ) to uranium-238 ( ). Assume: M _p = 1.007 825 u M _n = 1.008 665 u M_He = 4.002 603 u M_U = 238.050 786 u U = 1.66 × 10−²⁷ kg

How many grams of U-235 must be fissioned every day to produce 1000 MW of electricity in a nuclear power plant that is 1/3 efficient? [Assume 208 MeV/fission and 1 MeV = 1.6 × 10−¹³ J]

What is the disintegration energy (in MeV) associated with this spontaneous decay? m_Nd = 143.910 083 u m_Ce = 139.905 434 u M_He = 4.002 603 u 1 u = 1.66 × 10−²⁷ kg

Find the number of nuclei per unit volume (n = nuclei/cm³) for lead. atomic weight = 202.7 Density = 11.5 g/cm³ Avogadro's number = 6.02 × 10²³