Deck 29: Nuclear Physics

Question 1

The alpha radiation first classified by Rutherford was in fact which of the following?

A)helium nuclei
B)high energy quanta
C)electrons
D)positrons

Answer 1

helium nuclei

Question 2

The ratio of the numbers of neutrons to protons in the nucleus of naturally occurring isotopes tends to vary with atomic number in what manner?

A)increases with greater atomic number
B)decreases with greater atomic number
C)is maximum for atomic number = 60
D)remains constant for entire range of atomic numbers

Answer 2

increases with greater atomic number

Question 3

Rutherford's experiments involving the use of alpha particle beams directed onto thin metal foils demonstrated the existence of which of the following?

A)neutron
B)proton
C)nucleus
D)positron

Answer 3

nucleus

Question 4

The experiment, which gave the first evidence for the existence of the atomic nucleus, involved which of the following?

A)x-ray scattering
B)radioactive dating
C)cosmic ray detection
D)alpha scattering

Question 5

The mass of ¹²C is 12 u where 1 u = 1.660 559 * 10^-27 kg.This mass is equal to:

A)the mass of the ¹²C nucleus.
B)the mass of the ¹²C nucleus plus 6 electrons.
C)the mass of the ¹²C nucleus plus 12 electrons.
D)the mass of 6 protons and 6 neutrons.

Question 6

The atomic number of a given element is equivalent to which of the following?

A)proton number in the nucleus
B)neutron number in the nucleus
C)sum of the protons and neutrons in the nucleus
D)number of electrons in the outer shells

Question 7

If there are 146 neutrons in ²³⁸U, how many neutrons are found in the nucleus of ²³⁵U?

A)141
B)143
C)145
D)147

Question 8

The gamma radiation first classified by Rutherford was in fact which of the following?

A)helium nuclei
B)high energy quanta
C)electrons
D)positrons

Question 9

Neglecting recoil of the gold nucleus, how much kinetic energy must an alpha particle (charge = 2 * 1.6 * 10^-19 C) have to approach to within 1.00 * 10^-14 m of a gold nucleus (charge = 79 * 1.6 * 10^-19 C)? (k_e = 8.99 * 10⁹ N*m²/C² and 1 MeV = 1.6 * 10^-13 J)

A)11.7 MeV
B)14.6 MeV
C)18.2 MeV
D)22.7 MeV

Question 10

The binding energy of a nucleus is equal to:

A)the energy needed to remove one of the nucleons.
B)the average energy with which any nucleon is bound in the nucleus.
C)the energy needed to separate all the nucleons from each other.
D)the mass of the nucleus times c².

Question 11

The isotope ⁶⁴Zn has a nuclear radius of 4.8 * 10^-15 m.Approximately what is the nuclear radius of the isotope ²⁷Al?

A)2.0 * 10^-15 m
B)2.7 * 10^-15 m
C)3.6 * 10^-15 m
D)4.0 * 10^-15 m

Question 12

The atomic mass number of a nucleus is equivalent to which of the following numbers?

A)number of neutrons present
B)number of protons present
C)difference in neutron and proton numbers
D)sum of neutron and proton numbers

Question 13

What is the binding energy per nucleon of ¹⁹⁷Au (atomic number = 79)? (The following information regarding atomic masses will be needed: ¹⁹⁷Au, 196.966 543 u; hydrogen, 1.007 825 u; neutron, 1.008 665 u; also 1 u = 931.5 MeV/c²)

A)7.3 MeV
B)7.7 MeV
C)7.9 MeV
D)8.3 MeV

Question 14

The isotope ⁶⁴Zn has a nuclear radius of 4.8 *10^-15 m.Which of the following is the mass number of an isotope for which the nuclear radius is 7.2 *10^-15 m?

A)144
B)96
C)125
D)216

Question 15

What energy must be added or given off in a reaction where two hydrogen atoms and two neutrons are combined to form a helium atom? (Atomic masses for each: hydrogen, 1.007 825 u; neutron, 1.008 665 u; helium, 4.002 602 u; also, 1 u = 931.5 MeV/c²)

A)20.7 MeV added
B)20.7 MeV given off
C)28.3 MeV given off
D)28.3 MeV added

Question 16

For every stable nucleus except hydrogen, if the number of nucleons is doubled, the quantity that will change least is the:

A)mass.
B)charge.
C)volume.
D)density.

Question 17

The molecular mass for chlorine is not an integer multiple of the molecular mass of hydrogen but is about 35.5 times the molecular mass of hydrogen.This is primarily because:

A)the proton and neutron have different masses.
B)there are different isotopes of chlorine.
C)of the binding energy of the chlorine nucleus.
D)the chlorine nucleus has 35.5 nucleons.

Question 18

The nucleus of an atom is made up of which of the following?

A)electrons and protons
B)electrons and neutrons
C)protons, electrons and neutrons
D)protons and neutrons

Question 19

The beta radiation first classified by Rutherford was in fact which of the following?

A)helium nuclei
B)high energy quanta
C)electrons
D)positrons

Question 20

Certain stars at the end of their lives are thought to collapse combining their protons and electrons together to form a neutron star.Such a star could be thought of as a giant atomic nucleus.If a star of mass equal to that of the sun (M = 1.99 * 10³⁰ kg) collapsed into neutrons (m_n = 1.67 * 10^-27 kg), what would be the radius of such a star? (Hint: r = r₀A^1/3, where r₀ = 1.20 * 10^-15 m).

A)25.4 km
B)18.7 km
C)12.7 km
D)6.40 km

Question 21

Tritium is radioactive with a half-life of 12.33 years decaying into 3He with low-energy electron emission.If we have a sample of 3.00 * 10¹⁸ tritium atoms, what is its activity in decays/second? (1 year = 3.15 * 10⁷ s)

A)4.20 * 10¹⁰/second
B)5.35 * 10⁹ /second
C)3.69 * 10⁸/second
D)6.64 * 10⁷/second

Question 22

There are samples of two different isotopes, X and Y.Both contain the same number of radioactive atoms.Sample X has a half-life twice that of Y.How do their decay rates compare?

A)X has a greater rate than Y.
B)X has a smaller rate than Y.
C)The rates of X and Y are equal.
D)The rate depends on atomic number, not half-life.

Question 23

The half-life of ¹⁸N is 0.62 s. What is the decay constant for this isotope?

A)0.43 s^-1
B)1.1 s^-1
C)1.7 * 10^-11 Ci
D)The decay constant is not defined for a half-life of less than one second.

Question 24

A pure sample of ²²⁶Ra contains 2.0 * 10¹⁴ atoms of the isotope.If the half-life of ²²⁶Ra = 1.6 * 10³ years, what is the decay rate of this sample? (1 Ci = 3.7 * 10¹⁰ decays/s)

A)2.7 * 10^-12 Ci
B)3.4 * 10^-10 Ci
C)7.4 * 10^-8 Ci
D)9.6 * 10^-6 Ci

Question 25

A radioactive material initially is observed to have an activity of 1 000 decays/sec.If three hours later it is observed to have an activity of 125 decays/sec, what is its half-life?

A)1/2 hour
B)1 hour
C)3 hours
D)8 hours

Question 26

Approximately how many half-life periods must elapse if the activity of a radioactive isotope sample is to be reduced to 0.004 of the original value?

A)3
B)6
C)8
D)60

Question 27

If the stable nuclei are plotted with neutron number vs.proton number, the curve formed by the stable nuclei does not follow the line N = Z.This is predicted by examining how the binding energy is influenced by:

A)the volume of the nucleus.
B)the size of the nuclear surface.
C)the Coulomb repulsion.
D)the proton-neutron mass difference.

Question 28

The half-life of radioactive Technetium-99 is 6.0 hours.Find the number of ⁹⁹Tc nuclei necessary to produce a sample of activity 1.0 µCi.(1 Ci = 3.7 * 10¹⁰ decays/second)

A)8.0 * 10⁸
B)1.2 * 10⁹
C)2.1 * 10¹⁰
D)3.4 * 10¹¹

Question 29

The fact that the binding energy per nucleon does not depend very strongly on the volume of the nucleus indicates that:

A)the strong nuclear force saturates.
B)nucleons don't move throughout the nucleus.
C)all nuclei have the same volume.
D)the radius of a nucleus is directly proportional to the number of nucleons.

Question 30

A pure sample of ²²⁶Ra contains 2.0 * 10¹⁴ atoms of the isotope.If the half-life of ²²⁶Ra = 1.6 * 10³ years, what is the activity of this sample?

A)6.7 * 10⁹ decays/yr
B)8.7 * 10¹⁰ decays/yr
C)9.4 * 10¹⁰ decays/yr
D)13 * 10¹⁰ decays/yr

Question 31

Tritium has a half-life of 12.3 years.How many years will elapse when the radioactivity of a tritium sample diminishes to 20% of its original value?

A)21 years
B)29 years
C)57 years
D)86 years

Question 32

An element is emitting alpha, beta, and gamma radiation.Rank order them in terms of the thickness of protective shielding they will need for safety, from least to most.

A)alpha, beta and gamma
B)gamma, beta and alpha
C)beta, gamma and alpha
D)alpha, gamma and beta

Question 33

Calculate the binding energy per nucleon of the tritium nucleus, , given that the mass of the tritium nucleus is 3.016 05 u.(m_p = 1.007 276 u, mn = 1.008 665, and 1 u = 931.5 MeV/c²)

A)2.24 MeV/nucleon
B)2.45 MeV/nucleon
C)2.66 MeV/nucleon
D)2.86 MeV/nucleon

Question 34

1 Bq = ________ Ci?

A)1
B)10⁶
C)2.7 * 10^-11
D)3.7 * 10¹⁰

Question 35

The mass of ²³⁸U is not quite an integer multiple of ¹H mass.This is primarily because:

A)the proton and neutron have different masses.
B)there are several isotopes of uranium.
C)of the binding energy of uranium.
D)uranium is radioactive.

Question 36

An ancient building was known to have been built 3 000 years ago.Approximately what proportion of Carbon-14 atoms are yet in the building's wooden framing compared to the number which were present at the time of its construction? (half life of ¹⁴C = 5 730 years)

A)0.425
B)0.500
C)0.517
D)0.696

Question 37

If a fossil bone is found to contain 1/8th as much Carbon-14 as the bone of a living animal, what is the approximate age of the fossil? (half-life of ¹⁴C = 5 730 years)

A)7 640 years
B)17 200 years
C)22 900 years
D)45 800 years

Question 38

Tritium has a half-life of 12.3 years.What proportion of its original radioactivity will a sample have after 9 years?

A)0.55
B)0.60
C)0.73
D)0.84

Question 39

Approximately how many radioactive atoms are present in a tritium sample with an activity of 0.4 * 10^-6 Ci and a half-life of 12.3 years? (1 Ci = 3.7 * 10¹⁰ decays/s)

A)1.3 * 10⁸
B)7 * 10⁸
C)3 * 10¹⁰
D)8 * 10¹²

Question 40

Over the course of 3 hours, 15% of a radioactive material decays.What is its half-life?

A)4.1 hrs
B)12.8 hrs
C)24.0 hrs
D)68.6 hrs

Question 41

Of the main types of radiation emitted from naturally radioactive isotopes, which of the following is the most penetrating?

A)alpha
B)beta (electron)
C)gamma
D)beta (positron)

Question 42

A radioactive isotope that emits a gamma quantum will change in what respect?

A)Atomic number increases by one.
B)Atomic number decreases by one.
C)Atomic mass number decreases by one.
D)None of the above choices are valid.

Question 43

The existence of the neutrino was postulated to account for which basic conservation laws during the beta decay process?

A)conservation of energy
B)conservation of momentum
C)Both choices a and b are valid.
D)None of the above choices are valid.

Question 44

Chromium-55 (54.940 8 u) emits an electron leaving a daughter nucleus of manganese-55 (54.938 0 u).How much energy is released in this reaction? (1 u = 931.5 MeV/c²)

A)5.59 MeV
B)2.61 MeV
C)1.40 MeV
D)0.70 MeV

Question 45

The neutrino is:

A)a little neutron.
B)another name for a positron.
C)the particle detected in carbon dating.
D)a particle proposed to account for "missing" energy and momentum in beta decay.

Question 46

An alpha particle (mass = 6.68 * 10^-27 kg) is emitted from a radioactive nucleus with an energy of 5.00 MeV.How fast is the alpha particle moving in m/s? (1 MeV = 1.6 * 10^-13 J)

A)2.40 * 10⁷ m/s
B)1.55 * 10⁷ m/s
C)3.70 * 10⁶ m/s
D)1.85 * 10⁶ m/s

Question 47

What particle is emitted when ²⁰Na decays to ²⁰Ne? (atomic numbers of Na and Ne are, respectively, 11 and 10)

A)alpha
B)beta (electron)
C)beta (positron)
D)gamma quantum

Question 48

Tritium (³H) has a half-life of 12.3 years and releases 0.018 6 MeV energy per decay. What is the rate at which energy is released for a 1.0-gram sample of tritium? (N_A = 6.02 * 10²³ mol^-1, 1 year = 3.16 * 10⁷ s, 1 MeV = 1.6 * 10^-13 J, and m_t = 3.016 05 u)

A)1.1 W
B)9.6 W
C)3.2 W
D)0.33 W

Question 49

In the beta decay of ¹⁴C, the existence of the antineutrino was required to maintain:

A)energy conservation.
B)charge conservation.
C)conservation of the number of nucleons.
D)all of the above.

Question 50

The alpha emission process results in the daughter nucleus differing in what manner from the parent?

A)Atomic mass increases by one.
B)Atomic number decreases by two.
C)Atomic number increases by one.
D)Atomic mass decreases by two.

Question 51

Each of the three naturally occurring radioactive series start with one of the following isotopes except for which one?

A)(²³⁸U)
B)(²³⁵U)
C)(²³²Th)
D)(²³⁷Np)

Question 52

The neutron is radioactive and can beta decay to form a proton.This can occur primarily because:

A)the proton has less mass than a neutron.
B)there are several hydrogen isotopes.
C)of the binding energy of hydrogen.
D)the neutron is neutral.

Question 53

When radium-224 emits an alpha particle, the remaining daughter nucleus is which of the following?

A)lead-213
B)actinium-215
C)radon-220
D)bismuth-215

Question 54

Tritium (³H) has a half-life of 12.3 years and releases 0.018 6 MeV energy per decay. What is the activity of a 1.0-gram sample of tritium? (N_A = 6.02 * 10²³ mol^-1, 1 year = 3.16 * 10⁷ s, 1 MeV = 1.6 * 10^-13 J, and m_t = 3.016 05 u)

A)1.1 * 10¹⁵ Bq
B)3.2 * 10¹⁵ Bq
C)3.6 * 10¹⁴ Bq
D)1.3 * 10¹⁶ Bq

Question 55

The original nucleus and the final nucleus will be different isotopes of the same element for which decay scheme of the original nucleus?

A)alpha decay followed by two beta (electron) decays
B)two gamma decays
C)a beta (electron) decay followed by an alpha decay
D)a beta (electron) decay followed by neutron emission

Question 56

The beta emission process results in the daughter nucleus differing in what manner from the parent?

A)Atomic mass changes by one.
B)Atomic number changes by two.
C)Atomic number changes by one.
D)Atomic mass changes by two.

Question 57

What particle is emitted when ²⁴⁰Pu decays to ²³⁶U? (atomic numbers of Pu and U are, respectively, 94 and 92)

A)alpha
B)beta (electron)
C)beta (positron)
D)gamma quantum

Question 58

A radioactive isotope that emits an alpha particle will change in what respect?

A)Atomic number decreases by four.
B)Mass number decreases by four.
C)Both choices a and b are valid.
D)None of the above choices are valid.

Question 59

Uranium-238 decays to Thorium-234 by emitting which of the following?

A)beta
B)alpha
C)gamma
D)positron

Question 60

A 1-gram sample of wood is taken from an ancient site.If the Carbon-14 activity of the sample is 12.5% that of present-day organic material, what is the age of the wood? (T_1/2 for ¹⁴C is 5 730 years)

A)4 460 years
B)8 600 years
C)13 150 years
D)17 200 years

Question 61

What is the Q value of the reaction ? The mass of the alpha particle is 4.002 602 u, of the nitrogen is 14.003 074 u, of the oxygen is 15.994 915 u, and of the hydrogen is 2.014 102 u.(1 u = 931.5 MeV/c²)

A)-3.34 MeV
B)3.34 MeV
C)-3.11 MeV
D)3.11 MeV

Question 62

In the four radioactive series, the nuclei decay by either emitting alpha particles or beta particles until they reach the stable end product.Each decay, therefore, results in a mass number change of either 4 (for alpha decay) or 0 (for beta decay).The radium isotope ²²⁶Ra is in one of these series.What is the starting isotope in the series containing ²²⁶Ra?

A)(²³⁸U)
B)(²³⁵U)
C)(²³²Th)
D)(²³⁷Np)

Question 63

Two nuclei collide, one originally at rest, in an endothermic nuclear reaction with Q = -2.05 MeV.Which of the following describes the minimum kinetic energy needed in the reactant nuclei for the reaction is to occur?

A)equal to 2.05 MeV
B)greater than 2.05 MeV
C)less than 2.05 MeV
D)exactly half of 2.05 MeV

Question 64

The Q of a nuclear reaction is equal to:

A)the total charge involved.
B)energy associated with the change in mass.
C)energy associated with momentum conservation.
D)the exothermic endothermy.

Question 65

The Q value of the reaction is -1.65 MeV.What is the threshold energy of this reaction? (Hint: Once the Q value is known, the relative mass numbers are precise enough to yield the result to 3 significant figures, actual masses not being needed).

A)1.65 MeV
B)1.89 MeV
C)1.77 MeV
D)1.41 MeV

Question 66

Which of the following is not a unit of radiation dose?

A)rem
B)roentgen
C)rad
D)RBE

Question 67

Two different nuclei emit alpha particles, the energy released in each of these decays being the same.Which of the following has the highest resulting kinetic energy?

A)The lighter daughter nucleus.
B)The heavier daughter nucleus.
C)The alpha particle from the lighter nucleus.
D)The alpha particle from the heavier nucleus.

Question 68

What is the Q-value for the reaction where the products are 0.005 0 u less than the reactants? (1 u = 931.5 MeV/c²)

A)8.5 MeV
B)7.6 MeV
C)5.2 MeV
D)4.7 MeV

Question 69

If the sum total mass of reactants in a nuclear reaction is greater than that of product particles, then which of the following statements best describes the conditions of the reaction?

A)reaction is exothermic
B)reaction is endothermic
C)atomic number of each reactant must be greater than 40
D)atomic number of each reactant must be less than 80

Question 70

The isotope ²³⁸U, which starts one of the natural radioactive series, decays first by alpha decay followed by two negative beta decays.At this point, what is the resulting isotope?

A)(²³⁸U)
B)(²³⁶U)
C)(²³⁴Th (Z = 90 for Th.))
D)Some other uranium isotope not given above.

Question 71

Which of the following is not true for both the photon and the neutrino.

A)Both are uncharged.
B)Both have spin .
C)Both can carry different amounts of momentum.
D)Choose this answer if all of the above are true.

Question 72

A particle is fired at a target nucleus in which a reaction that could occur has a negative Q value.Which of the following statements is true?

A)The kinetic energy of the bombarding particle can be any amount for the reaction to occur.
B)The kinetic energy of the bombarding particle must be equal to the absolute value of the Q value for the reaction to occur.
C)The kinetic energy of the bombarding particle was greater than the absolute value of the Q value if the reaction occurred.
D)The Q value has nothing to do with whether or not the reaction can occur.

Question 73

Genetic radiation damage is:

A)another name for somatic damage.
B)any radiation damage to a cell.
C)radiation damage affecting reproductive cells.
D)measured in roentgens.

Question 74

A proton is captured by an oxygen-16 atom which in turn emits a deuteron.What is the element and mass number of the product isotope?

A)nitrogen-15
B)oxygen-17
C)oxygen-15
D)fluorine-15

Question 75

In the reaction , what is the mass number and atomic number of the product designated by X?

A)102, 42
B)101, 42
C)102, 44
D)not given

Question 76

Sample #1 is made from an isotope with decay constant and sample #2 is made from an isotope with decay constant , where .Which of the following statements must be true?

A)The activity of sample #1 is greater than that of sample #2.
B)The activity of sample #2 is greater than that of sample #1.
C)The half-life exhibited for sample #1 is greater than that of sample #2.
D)The half-life exhibited for sample #2 is greater than that for sample #1

Question 77

A rad is that amount of radiation that:

A)produces 2.08 * 10⁹ ion pairs per cm³ in air under standard conditions.
B)deposits 8.76 * 10^-3 J of energy into 1 kg of air.
C)deposits 10^-2 J of energy into 1 kg of absorbing material.
D)is also known as a rem.

Question 78

The isotope ¹⁴C cannot be used in dating old samples of which of the following?

A)charcoal from a fire
B)a bronze implement from a cave
C)a bone buried in mud
D)All of the above can be dated using ¹⁴C.

Question 79

To what is the radiation damage in biological organisms primarily due?

A)helium introduction
B)heating
C)induced radioactivity
D)ionization