Deck 30: Nuclear Physics

Question 1

The symbol for a certain isotope of radium is Ra. How many nucleons are there in the nucleus of this isotope?

A) 88
B) 138
C) 214
D) 226
E) 314

Answer 1

D

Question 2

Name the first three isotopes of hydrogen, write their symbols in standard notation, and indicate which one is the most common and which one is the most unstable.

Answer 2

H is ordinary hydrogen, H is deuterium, and H is tritium. H is the most common and H is the most unstable.

Question 3

The primary reason that very large nuclei are unstable is due to

A) the cumulative repulsive force of the protons.
B) the cumulative attractive force between the protons and the orbiting electrons.
C) the repulsive force between the neutrons and the protons.
D) the extreme weakness of the gravitational attraction of the protons.

Answer 3

A

Question 4

The atomic number and mass number for calcium-39 are 20 and 39, respectively. How many neutrons are in one atom?

A) 1
B) 19
C) 20
D) 39
E) 59

Question 5

The atomic number of an atom is equal to the number of what particles in the nucleus?

A) protons
B) neutrons
C) nucleons
D) electrons
E) positrons.

Question 6

What is true of an element of atomic number 15 that has an isotope of mass number 32? (There could be more than one correct choice.)

A) the number of protons in the nucleus is 15.
B) the number of neutrons in the nucleus is 15.
C) the number of protons in the nucleus is 32.
D) the number of nucleons in the nucleus is 47.
E) the number of neutrons in the nucleus is 17.

Question 7

The two strongest forces that act between protons in a nucleus are

A) the weak nuclear and electromagnetic forces.
B) the weak nuclear and the gravitational forces.
C) the electrostatic and the gravitational forces.
D) the strong nuclear and the electrostatic forces.

Question 8

An yttrium isotope has 39 protons and 50 neutrons in its nucleus. Which one of the following symbols accurately represents this isotope?

A) Y
B) Y
C) Y
D) Y
E) Y

Question 9

The main reason that there is a limit to the size of a stable nucleus is

A) the limited range of the gravitational force.
B) the short range nature of the strong nuclear force.
C) the weakness of the gravitational force.
D) the weakness of the electrostatic force.

Question 10

The atomic mass unit is defined as

A) the mass of a proton.
B) the mass of an electron.
C) the mass of a hydrogen-1 atom.
D) one twelfth the mass of a carbon-12 atom.
E) the mass of a carbon-12 nucleus.

Question 11

Atomic nuclei that are all isotopes of an element all have the same

A) number of nucleons.
B) mass.
C) number of protons.
D) number of neutrons.

Question 12

The symbol for a certain isotope of strontium is Sr. What is the mass number of this isotope?

A) 38
B) 52
C) 88
D) 90
E) 128

Question 13

In massive stars, three helium nuclei fuse together, forming a carbon nucleus, and this reaction heats the core of the star. The net mass of the three helium nuclei must therefore be

A) higher than that of the carbon nucleus.
B) less than that of the carbon nucleus.
C) the same as that of the carbon nucleus because mass is always conserved.
D) the same as that of the carbon nucleus because energy is always conserved.

Question 14

Which of the following statements is not true of the strong nuclear force?

A) The nuclear force has a short range, of the order of nuclear dimensions.
B) For two protons that are very close together, the nuclear force and the electric force have about the same magnitudes.
C) The nuclear force does not depend on charge.
D) A nucleon in a large nucleus interacts via the nuclear force only with nearby nucleons, not with ones far away in the nucleus.
E) The nuclear force affects both neutrons and protons.

Question 15

Write the standard nuclear notation for the following nuclei: hydrogen-2, sulfur-33, and lead-207.

Question 16

In a Nb nucleus, how many protons, neutrons, and electrons are found there?

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

Question 17

All nuclei of a given element have the same number of

A) neutrons.
B) protons.
C) nucleons.
D) protons + neutrons.

Question 18

The symbol for a certain isotope of polonium is Po. How many neutrons are there in the nucleus of this isotope?

A) 84
B) 130
C) 214
D) 298
E) 314

Question 19

A stable nucleus contains many protons very close to each other, all positively charged. Why do the protons not fly apart due to mutual Coulomb repulsion?

A) An attractive nuclear force in the nucleus counteracts the effect of the Coulomb forces.
B) There are an equal number of electrons in the nucleus which neutralize the protons.
C) The neutrons in the nucleus shield the protons from each other.
D) The Coulomb force does not operate within nuclei.
E) The gravity of the protons and neutrons overcomes their repulsion at such close distances.

Question 20

The mass number of an atom is equal to the number of what particles in the nucleus?

A) protons
B) neutrons
C) nucleons
D) electrons
E) positrons.

Question 21

What are the mass number, the atomic number, and neutron number for each of the following particles?
(a) proton
(b) neutron
(c) alpha particle

Question 22

What are the mass number A and the charge (in units of e) for each of the following particles or rays?
(a) beta-plus
(b) beta-minus
(c) gamma ray

Question 23

In beta-minus decay

A) a proton is emitted.
B) a neutron is emitted.
C) an electron is emitted.
D) an electron decays into another particle.
E) a proton is transformed into a neutron.

Question 24

What is the mass number of alpha particles?

A) 1
B) 2
C) 3
D) 4
E) 6

Question 25

A β^- particle is also known as

A) an electron.
B) a positron.
C) a helium nucleus.
D) a high-energy photon.

Question 26

In β^- decay, the number of protons in the nucleus is

A) decreased by 1.
B) decreased by 2.
C) increased by 1.
D) increased by 2.
E) remains unchanged.

Question 27

A β⁺ particle is also known as

A) an electron.
B) a positron.
C) a helium nucleus.
D) a high-energy photon.

Question 28

A fusion reaction releases energy because the binding energy of the resulting nucleus

A) is greater than the binding energy of the original nuclei.
B) is equal to the binding energy of the original nuclei.
C) is less than the binding energy of the original nuclei.
D) is released in the process.
E) is absorbed in the process.

Question 29

When a β^- particle is emitted from an unstable nucleus, the atomic number of the nucleus

A) increases by 1.
B) decreases by 1.
C) increases by 2.
D) decreases by 2.
E) does not change.

Question 30

During β⁺ decay

A) a neutron is transformed to a proton.
B) a proton is transformed to a neutron.
C) a neutron is ejected from the nucleus.
D) a proton is ejected from the nucleus.
E) the number of nucleons decreases.

Question 31

In β^- decay, the number of neutrons in the nucleus is

A) decreased by 1.
B) decreased by 2.
C) increased by 1.
D) increased by 2.
E) remains unchanged.

Question 32

In positron decay, the number of protons in the nucleus is

A) decreased by 1.
B) decreased by 2.
C) increased by 1.
D) increased by 2.
E) remains unchanged.

Question 33

When a β^- particle is emitted from an unstable nucleus, the atomic mass number of the nucleus

A) increases by 1.
B) decreases by 1.
C) increases by 2.
D) does not change.

Question 34

An α particle is also known as

A) an electron.
B) a positron.
C) a helium nucleus.
D) a high-energy photon.

Question 35

When a β⁺ particle is emitted from an unstable nucleus, the atomic number of the nucleus

A) increases by 1.
B) decreases by 1.
C) increases by 2.
D) decreases by 2.
E) does not change.

Question 36

The nuclei of He are also known as

A) α particles.
B) β particles.
C) γ rays.
D) x-rays.
E) positrons.

Question 37

The binding energy per nucleon of a nucleus

A) increases steadily as we go to heavier elements.
B) decreases steadily as we go to heavier elements.
C) is approximately constant throughout the periodic table, except for very light nuclei.
D) has a maximum near iron in the periodic table and decreases after that for heavier elements.
E) has a minimum near iron in the periodic table and increases after that for heavier elements.

Question 38

A radioactive isotope of atomic number Z emits an alpha particle, and the daughter nucleus then emits a beta-minus particle. What is the atomic number of the resulting nucleus?

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

Question 39

During β^- decay

A) a neutron is transformed to a proton.
B) a proton is transformed to a neutron.
C) a neutron is ejected from the nucleus.
D) a proton is ejected from the nucleus.
E) the number of nucleons increases.

Question 40

A gamma ray is also known as

A) an electron.
B) a positron.
C) a helium nucleus.
D) a high-energy photon.

Question 41

The half-life of cobalt-60 is 5.3 years, while that of strontium-90 is about 29 years. Suppose you have samples of both isotopes, and that they initially have the same activity (number of decays per second). What must be true of the numbers of cobalt-60 and strontium-90 nuclei in these 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 42

The chief hazard of radiation damage to living cells is

A) due to heating.
B) due to ionization.
C) due to the creation of chemical impurities.
D) the creation of new isotopes within the body.
E) the creation of radioactive material within the body.

Question 43

Suppose the half-life of an isotope is 2 days. You purchase 10 grams of the isotope, but it was produced in a laboratory 4 days before it was delivered to you. How much of this isotope will you have 3 days after it was delivered to you?

A) more than 2.5 grams but less than 5 grams
B) 2.5 grams
C) more than 1.25 grams but less than 2.5 grams
D) 1.25 grams
E) less than 1.25 grams

Question 44

The half-life of cobalt-60 is 5.3 years, while that of strontium-90 is about 29 years. Suppose you have samples of both isotopes, and that they initially contain equal numbers of atoms of these isotopes. How will the activities (number of decays per second) of the samples compare?

A) The activity of the cobalt-60 sample will be greater.
B) The activities cannot be compared without more information.
C) The activities will be equal.
D) The activity of the strontium-90 sample will be greater.

Question 45

A β^- decay occurs in an unstable nucleus when

A) a proton is converted to an electron by the strong force.
B) a proton is converted to a neutron by the strong force.
C) a neutron is converted to a proton by the weak force.
D) a neutron is converted to an alpha particle by the weak force.
E) a neutron is converted to a positron by the weak force.

Question 46

Two radioactive isotopes, X and Y, both decay to stable products. The half-life of X is about a day, while that of Y is about a week. Suppose a radioactive sample consists of a mixture of these two nuclides. If the mixture is such that the activities arising from X and Y are initially equal, then a few days later the activity of the sample will be due

A) predominantly to Y.
B) predominantly to X.
C) entirely to Y.
D) to X and Y equally.

Question 47

Carbon-14 decays by β^- emission. What nucleus is left after this decay?

A) carbon-13
B) carbon-14
C) carbon-15
D) nitrogen-14
E) nitrogen-15

Question 48

The atom Fr decays to Ra by emitting what kind of nuclear radiation?

A) alpha
B) beta-minus
C) beta-plus
D) gamma
E) x-rays.

Question 49

Modern in-air nuclear bomb tests have created an extra high level of ¹⁴C in our atmosphere. If future archaeologists date samples from this era, without knowing of this testing, will their carbon-14 dates be too young, too old, or correct? If correct, why?

A) Too young.
B) Too old.
C) Correct, since ¹⁴C from bomb tests is different from that produced naturally.
D) Correct, because modern biological materials do not gather ¹⁴C from bomb tests.

Question 50

A person receives an absorbed dose of protons of 20 millirads. The RBE of protons is 5. What is this person's equivalent dose in rem?

A) 4 millirem
B) 15 millirem
C) 20 millirem
D) 25 millirem
E) 100 millirem

Question 51

What happens to the half-life of a radioactive substance as it decays?

A) It remains constant.
B) It increases.
C) It decreases at a constant rate.
D) It decreases at an exponential rate.

Question 52

Polonium-216 decays to lead-212 by emitting what kind of nuclear radiation?

A) alpha
B) beta-minus
C) beta-plus
D) gamma
E) x-rays.

Question 53

How many protons, neutrons, and nucleons are there in a carbon-14 nucleus?

Question 54

When an unstable nucleus decays by emitting an alpha particle, the atomic mass number A of the nucleus

A) increases by 4.
B) increases by 2.
C) decreases by 2.
D) decreases by 4.
E) remains unchanged.

Question 55

A radioactive isotope of atomic number Z emits a beta-minus particle, and then the daughter nucleus emits a gamma ray. What is the atomic number of the resulting nucleus after both processes?

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

Question 56

When an unstable nucleus decays by emitting an alpha particle, the atomic number Z of the nucleus

A) increases by 4.
B) increases by 2.
C) decreases by 2.
D) decreases by 4.
E) remains unchanged.

Question 57

What happens to the half-life of a radioactive substance as we increase its temperature?

A) It does not change.
B) It increases.
C) It decreases at a constant rate.
D) It decreases at an exponential rate.

Question 58

Inside the nucleus, the strongest of the four fundamental forces is

A) the weak nuclear force.
B) the electromagnetic force.
C) the gravitational force.
D) the strong nuclear force.

Question 59

Inside the nucleus, the weakest of the four fundamental forces is

A) the weak nuclear force.
B) the electromagnetic force.
C) the gravitational force.
D) the strong nuclear force.

Question 60

If the half-life of a material is 45 years, how much of it will be left after 100 years?

A) more than 1/2
B) less than 1/2 but more than 1/4
C) more than 1/4 but less than 1/2
D) less than 1/4 but more than 1/8
E) less than 1/8

Question 61

In a head-on collision, an alpha particle (Z = 2) of energy bounces straight back from a nucleus of charge How close were the centers of the objects at closest approach? (1 eV = 1.60 × 10^-19 J, e = 1.60 × 10^-19 C, 1/4πε₀ = 8.99 × 10⁹ N ∙ m²/C²)

A) 2.81 × 10^-14 m
B) 3.39 × 10^-12 m
C) 6.56 × 10^-15 m
D) 2.17 × 10^-14 m

Question 62

A beryllium-8 nucleus at rest undergoes double alpha decay as follows: Be → He + He The known atomic masses are: He: 4.002603 u Be: 8.005305 u
What is the kinetic energy of each departing alpha particle? (1 u = 931.5 MeV/c²)

A) 46 keV
B) 65 keV
C) 92 keV
D) 130 keV
E) 180 keV

Question 63

What combination of quarks produces a proton and what are the electric charges on these quarks, expressed in terms of e?

Question 64

What are the possible charges of a quark (not an antiquark)?

A) -e, 0, e
B) -2/3 e, -1/3 e, +1/3 e, +2/3 e
C) -2/3 e, +1/3 e
D) -1/3 e, +2/3 e
E) -1/3 e, +1/3 e

Question 65

In the first nuclear reaction observed, physicists saw an alpha particle (Z = 2) interact with a nitrogen nucleus in air (Z = 7) to produce a proton. The energy of the alpha particle was enough to enable the nuclei to touch in spite of the Coulomb repulsion. What distance (in fm) between the centers of the alpha particle and the nitrogen was reached? This determines a limit on the radius of the nitrogen nucleus. (1 eV = 1.60 × 10^-19 J, e = 1.60 × 10^-19 C, 1/4πε₀ = 8.99 × 10⁹ N ∙ m²/C²)

A) 0 fm
B) 0 fm
C) 0 fm
D) 0 fm

Question 66

The proton is made up of which one of the following quark combinations (up, down, strange, charm, top, bottom)?

A) uud
B) ddu
C) udd
D) ttb
E) bst

Question 67

What combination of quarks produces a neutron and what are the electric charges on these quarks, expressed in terms of e?

Question 68

A summary of the nuclear reactions that power our sun is 4p → ⁴He + 2e^-, with masses of 938.272 MeV/c² for a proton, 3727.38 MeV/c² for the helium nucleus, and 0.511 MeV/c² for each electron. How much energy is released by each of these reactions?

A) 24.69 MeV
B) 28.3 MeV
C) 2790.13 MeV
D) 279.01 MeV

Question 69

The neutron is made up of which one of the following quark combinations (up, down, strange, charm, top, bottom)?

A) uud
B) ddu
C) udd
D) ttb
E) bst

Question 70

Which of the following particles are leptons? (There may be more than one correct choice.)

A) protons
B) neutrons
C) electrons
D) photons
E) quarks

Question 71

Elementary particles that experience the weak nuclear force but not the strong nuclear force are called

A) leptons.
B) hadrons.
C) mesons.
D) bosons.
E) baryons.

Question 72

One of the fusion reactions that occurs in the sun is: He + He → He + H + H The following atomic masses are known: H: 1.007825 u He: 3.016029 u He: 4.002603 u
What is the reaction energy released in this fusion reaction? (1 u = 931.5 MeV/c²)

A) 11 MeV
B) 13 MeV
C) 15 MeV
D) 17 MeV
E) 19 MeV

Question 73

Which of the following particles are not made up of quarks? (There could be more than one correct choice.)

A) alpha particle
B) electron
C) proton
D) positron
E) neutron

Question 74

Which of the following particles (or groups of particles) are made up of quarks?

A) protons, neutrons, and electrons
B) electrons and neutrinos
C) photons
D) protons and neutrons
E) All particles except for photons are made up of quarks.

Question 75

How many quarks are in a deuteron, H?

A) 2
B) 3
C) 4
D) 6
E) 9

Question 76

How many quarks are in a tritium isotope, H?

A) 2
B) 3
C) 4
D) 6
E) 9

Question 77

Leptons can interact by which of the following forces?

A) strong nuclear force, weak nuclear force, electromagnetic force, gravitation
B) strong nuclear force, weak nuclear force, electromagnetic force
C) weak nuclear force, electromagnetic force, gravitation
D) strong nuclear force, weak nuclear force
E) strong nuclear force, electromagnetic force, gravitation

Question 78

The diameter of an atom is 1.4 × 10^-10 m and the diameter of its nucleus is 1.0 × 10^-14 m. What fraction of the atom's volume is occupied by its nucleus?

A) 3.6 × 10^-13
B) 7.1 × 10^-5
C) 5.1 × 10^-9
D) 2.6 × 10^-17

Question 79

How much energy is released when 0.60 μg of ³H have decayed to ³He? The mass of ³He is 3.0160293 u, the mass of ³H is 3.0160492 u, 1 u = 931.5 MeV/c², 1 eV = 1.60 × 10^-19 J, and N_A = 6.022 × 10²³ molecules/mol.

Question 80

The radius R of a nucleus of mass number A is given by R = R₀ A^1/3, where R₀ = 1.2 × 10^-15 m, calculate the density of a nucleus that has contains 57 protons and 82 neutrons. The mass of a nucleon (proton or neutron) is 1.67 × 10^-27 kg.