Deck 30: Nuclear Energy and Elementary Particles

Question 1

When uranium fissions into two medium-mass nuclei,the product nuclei tend to have an excess of neutrons when compared to stable nuclei.What type of radioactive decay would one expect from these product nuclei?

A)meson decay
B)negative beta decay
C)positive beta decay
D)proton decay

Answer 1

negative beta decay

Question 2

Assume that (i)the energy released per fission event of ²³⁵U is 194 MeV,and (ii)33% of the nuclear energy released in a power plant is ultimately converted to usable electrical energy.Approximately how many fission events will occur in one second in order to provide the two-GW electrical power output of a typical power plant? (1 eV = 1.6 × 10−¹⁹ J)

A)4E+23 fission/s
B)2E+20 fission/s
C)6E+25 fission/s
D)2E+15 fission/s
E)​8E+17 fission/s

Answer 2

2E+20 fission/s

Question 3

The K-ratio in a uranium fuel reactor is defined as the average number of neutrons from each fission event that will cause another event.In a well-functioning reactor,it is desired that the K-ratio have what value?

A)zero
B)0.5
C)1.0
D)2.0

Answer 3

1.0

Question 4

A capture by a target nucleus of uranium-235 is most apt to occur for which type of "bullet" particle?

A)low velocity alpha particle
B)low velocity proton
C)high velocity neutron
D)low velocity neutron

Question 5

A plasma can be contained in a "magnetic bottle" because it has which of the following properties?

A)high temperature
B)liquid in form
C)made of charged particles
D)made of light elements

Question 6

Which of the following will not influence the rate at which nuclear reactions will occur in a nuclear power plant where the fuel elements are a mixture of ²³⁵U and ²³⁸U?

A)the presence of moderating material
B)the presence of control rods
C)the percentage of ²³⁵U relative to ²³⁸U
D)the percentage of the energy that is used to produce electricity

Question 7

The advantage of a fusion reactor when compared to a fission reactor is which of the following?

A)The fuel is cheaper.
B)There is less radioactive waste material.
C)Both choices above are valid.
D)None of the above choices are valid.

Question 8

In a nuclear fission process involving the use of ²³⁹Pu fuel,if the approximate average binding energy per nucleon in the product fragments is 8.8 MeV while that of the fuel atom is 8.1 MeV,what approximate net energy is released per fission?

A)170 MeV
B)270 MeV
C)190 MeV
D)90 MeV
E)​50 MeV

Question 9

In a fission reaction,a ²³⁵U nucleus captures a neutron.This results in the creation of the products ¹⁴¹Ba and ⁹²Kr along with how many neutrons?

A)1
B)2
C)3
D)5

Question 10

One in 4 600 water molecules contains a deuterium atom.If all the deuterium could be extracted from 1 m³ of water and then reacted,how much energy could be obtained? (Each D-D fusion liberates 3.65 MeV of energy,1 MeV = 1.6 × 10^-13 J,ρ_{water =} 10³ kg/m³,one mole of water has a mass of 18 g,and ​N_A ​= 6.02 × 10²³)

A)4.2E+12 J
B)1.3E+25 J
C)3.5E+11 J
D)2.1E+12 J
E)​6.9E+14 J

Question 11

In a fission reaction,a ²³⁵U nucleus captures a neutron.What energy is released if the products are ¹³⁹I,⁹⁵Y and two neutrons? (atomic masses: ²³⁵U,235.043 9;¹³⁹I,138.935 0;⁹⁵Y,94.913 4;neutron,1.008 67;and 1 u = 931.5 MeV/c²)

A)123 MeV
B)174 MeV
C)199 MeV
D)218 MeV

Question 12

In order to be useful in sustaining a reaction,the neutrons in a fission reactor must be

A)released from the reactor.
B)warmed to a higher temperature.
C)accelerated.
D)decelerated.

Question 13

Calculate the energy (in kW⋅h)given off if five kg of plutonium-239 undergoes complete fission.The energy released per fission is 200 MeV.(1 MeV = 1.6 × 10−¹³ J)

A)1.1E+11 kW⋅h
B)6.4E+12 kW⋅h
C)1.6E+16 kW⋅h
D)1.1E+8 kW⋅h
E)5.4E+9 ​kW⋅h

Question 14

In a fusion reactor,the high temperature of the order of 10⁸ K is required in order that what condition is met?

A)melt down the hydrogen fuel
B)strip the hydrogen atoms of their electrons
C)break the protons into their elementary particle sub-parts
D)overcome Coulomb repelling forces between protons

Question 15

If a self-sustained controlled fusion reaction is to operate,a condition which must be met is that the fuel material be subjected to which of the following condition(s)?

A)confined for sufficient time period
B)have sufficiently high density
C)be at sufficiently high temperature
D)All of the above choices are valid.

Question 16

When comparing product nuclei to reactant nuclei in an exothermal nuclear fusion process,which has the greater binding energy per nucleon?

A)greater in product nuclei
B)greater in reactant nuclei
C)equal in both product and reactant nuclei
D)None of the above choices are valid.

Question 17

How much kinetic energy must a deuterium ion (charge = 1.6 × 10^-19 C)have to approach within 1.7 × 10−¹⁴ m of another deuterium ion? (k_e = 8.99 × 10⁹ N·m²/C² and 1 keV = 1.6 × 10^-16 J)

A)50 keV
B)110 keV
C)10 keV
D)80 keV
E)​140 keV

Question 18

Calculate the energy released in the following fusion reaction where reactants are ⁶Li and a neutron;products are ⁴He and ³H.(atomic masses: ⁶Li,6.015 12;neutron,1.008 67;⁴He,4.002 60;³H,3.016 031;also 1 u = 931.5 MeV/c²)

A)2.95 MeV
B)4.81 MeV
C)8.63 MeV
D)17.2 MeV

Question 19

The average mass per nucleon is greatest in which of the following elements?

A)hydrogen
B)iron
C)uranium
D)krypton

Question 20

In a nuclear fusion reactor,the Lawson criterion prescribes the necessary conditions,as related to density and confinement time of the plasma fuel,in order that the process produces a net power output.If the fuel density were doubled,by what factor would the required confinement time change?

A)0.25
B)0.50
C)1.4
D)2.0

Question 21

Which force can act over distances comparable to the distance between planets?

A)only gravitational
B)only electrical
C)only magnetic
D)All of the above.

Question 22

Which of the following particles has not been observed experimentally?

A)photon
B)graviton
C)antiproton
D)Z⁰ boson

Question 23

Which of the following forces is the strongest at near distances?

A)gravitational
B)weak nuclear
C)strong nuclear
D)electromagnetic

Question 24

The exchange of mediating photons can produce

A)neither a repulsive nor an attractive force.
B)either a repulsive or an attractive force.
C)a repulsive force.
D)an attractive force.

Question 25

How fast is an ion of deuterium moving,assuming rms speed,if it is in a plasma with a temperature of 190 × 10⁶ K? (k_B = 1.38 × 10^-23 J/K and m_D​ = 2 × 1.66 × 10^-27 kg)

A)1.54E+6 m/s
B)1.54E+4 m/s
C)2.37E+12 m/s
D)8.89E+5 m/s
E)​2.80E+6 m/s

Question 26

A positron and an electron differ in

A)charge.
B)mass.
C)spin.
D)energy.

Question 27

What is meant by a particle being elementary?

A)It is too small to see.
B)It is subatomic.
C)It is not composed of other particles.
D)It has no charge.

Question 28

Assuming the Lawson criterion for the deuterium-tritium interaction,ητ ≥ 10¹⁴ s/cm³,what is the minimum plasma ion density at 10 ¹¹ K?

A)10^-3 s/cm³
B)10³ s/cm³
C)10²⁵ s/cm³
D)10³⁶ s/cm³
E)More information is needed.

Question 29

The size and sign of the charge on an electron is the same as that for

A)a positron.
B)an antiproton.
C)an antineutron.
D)an antineutrino.

Question 30

Theoretical physicists have had the greatest success in combining which force with the electromagnetic force?

A)strong nuclear force
B)weak nuclear force
C)gravitational force
D)the force caused by the exchange of gluons

Question 31

The weak force that acts between an electron and a quark is caused by the exchange of

A)photons.
B)gluons.
C)gravitons.
D)W⁺,W^-,or Z⁰ bosons.

Question 32

In the proton-proton cycle,the eventual product is

A)heavy hydrogen.
B)tritium.
C)helium-3.
D)helium-4.

Question 33

Which particle in the free state is least stable?

A)electron
B)photon
C)neutron
D)proton

Question 34

Which of the following particles is (are)considered to be elementary?

A)the neutron
B)the meson
C)the electron
D)All of the above.

Question 35

Which,if any,is an elementary particle?

A)the proton
B)the Ω^- particle
C)the muon
D)All three are not elementary particles.

Question 36

The strong force is mediated by

A)the gluon.
B)the W^- boson.
C)the W⁺ boson.
D)All of these choices.

Question 37

Theoretical physicists have had the least success in combining which force with the electromagnetic force?

A)strong nuclear force
B)weak nuclear force
C)gravitational force
D)electrical Coulomb force

Question 38

Which of the following forces is the weakest?

A)strong nuclear
B)weak nuclear
C)electromagnetic
D)gravitational

Question 39

The Dirac theory predicted that a positron would be

A)a negative electron in a negative energy state.
B)a particle with same mass as an electron but with opposite charge.
C)a particle with negative mass.
D)All of the above.

Question 40

If the lifetime of a particle is roughly inversely proportional to the relative strength of the force involved,then for the strong,electromagnetic,and weak forces,arrange the forces according to their resulting lifetimes ranging from shortest to longest lifetimes.

A)strong,electromagnetic,weak
B)weak,electromagnetic,strong
C)weak,strong,electromagnetic
D)strong,weak,electromagnetic

Question 41

If a negative muon decays to form an electron-antineutrino pair and one other particle,the other particle may be a(n)

A)positron.
B)antineutrino.
C)mu neutrino.
D)electron.

Question 42

The attractive force between protons and neutrons in the nucleus is brought about by the exchange of a virtual pi-meson (mπ = 140 MeV/c²).Estimate the longest time a π can exist in accordance with the uncertainty principle ΔE⋅Δt = h/2π.(h/2π = 1.05 × 10−³⁴ J⋅s,1 eV = 1.6 × 10−¹⁹ C)

A)3.3 × 10−¹⁸ s
B)2.4 × 10−²¹ s
C)4.7 × 10−²⁴ s
D)6.9 × 10−²⁷ s

Question 43

If a photon produces an electron-positron pair and one other particle,the other particle may be a(n)

A)muon.
B)antineutrino.
C)neutrino.
D)photon.

Question 44

A proton and antiproton each with total energy 300 GeV collide head-on.What is the total energy (particles + energy)released?

A)600 GeV
B)300 GeV
C)zero
D)450 GeV
E)​150 GeV

Question 45

A photon hits an electron,and an antiproton is created.Some uncharged particles must have left the collision.These may be

A)neutron and neutrino.
B)neutron and antineutrino.
C)photon and neutrino.
D)photon and antineutrino.

Question 46

"MeV/c²" is a unit for

A)energy.
B)mass.
C)momentum.
D)nuclear force.

Question 47

If protons have a half-life of 10³¹ years,what fraction of the original protons have decayed during the 10¹ year existence of the universe?

A)1/31
B)30/31
C)4 × 10^-7.5
D)4/10
E)l​ess than any of the above values

Question 48

Which of these particles has the least mass?

A)electron neutrino
B)muon
C)electron
D)pion

Question 49

Calculate the range of the force that might be produced by the virtual exchange of a proton.Assume ΔE⋅Δt = h/2π.(m_p = 1.67 × 10−²⁷ kg,c = 3.00 × 10⁸ m/s,and h/2π = 1.05 × 10−³⁴ J⋅s)

A)6.72 × 10−²⁵ m
B)2.10 × 10−¹⁶ m
C)6.00 × 10−⁸ m
D)1.54 × 10−¹⁵ m

Question 50

The virtual exchange of photons can produce

A)a repulsive force.
B)an attractive force.
C)either a repulsive or an attractive force.
D)neither a repulsive nor an attractive force.

Question 51

According to present theories,there is a neutrino for all the following particles except

A)the neutral pion.
B)the electron.
C)the muon.
D)the tau lepton.

Question 52

Which of the following is not a meson?

A)the muon
B)the pion
C)the kaon
D)All of the above are mesons.

Question 53

Which of these particles has the most mass?

A)pion
B)muon
C)electron
D)positron

Question 54

Which of the following is not conserved?

A)lepton number
B)baryon number
C)meson number
D)energy

Question 55

The pion (mπ = 140 MeV/c²)is thought to be the particle exchanged in the nuclear force.What is the maximum range of this particle if its "time of existence" is as long as can be allowed by the uncertainty principle ΔE⋅Δt = h/2π? (h/2π = 1.05 × 10−³⁴ J⋅s,c = 3.00 × 10⁸ m/s,and 1 eV = 1.6 × 10−¹⁹ J)

A)1.2 × 10−¹⁵ m
B)1.4 × 10−¹⁵ m
C)2.0 × 10−¹⁵ m
D)7.5 × 10−¹⁵ m

Question 56

Which particle was the last to be discovered?

A)electron
B)neutrino
C)neutron
D)proton

Question 57

A neutron and a proton have the same

A)charge.
B)half-life.
C)mass.
D)baryon number.

Question 58

The medical diagnostic technique PET stands for

A)proton energizing test.
B)phosphorus electron tracing.
C)precision electronic tracking.
D)positron emission tomography.

Question 59

A negative muon decays to form an electron and a mu neutrino and one additional particle.The other particle must be a(n)

A)positron.
B)antineutrino.
C)neutrino.
D)photon.

Question 60

Of the following mesons,which is its own antiparticle?

A)K^-
B)φ
C)π⁺
D)none of those given

Question 61

The following reaction can occur by the strong interaction: π⁰ + n → K⁺ + Σ^-.If the quark composition of the n is (udd),the π ⁰ is
And the composition of the K⁺ is
,what is the quark composition of the Σ^-?

A)uds
B)dds
C)sss
D)

Question 62

The spin of all quarks is

A)0.
B)1/2.
C)1.
D)1/3 or 2/3.

Question 63

​Consider the following reaction.
Π⁺ + n → π^- + p
This reaction is impossible because it violates which conservation law?

A)​baryon number
B)​lepton number
C)​strangeness
D)​charge
E)​two of the above

Question 64

According to the standard model,there are some cases in which a quark and its anti-quark have the same

A)charge.
B)baryon number.
C)strangeness.
D)All of the above are always different.

Question 65

Consider the following reaction.
N → p + e^-
This reaction is impossible because it violates which conservation law?​

A)​baryon number
B)​lepton number
C)​strangeness
D)​charge

Question 66

The constituent quarks of the proton are uud.What are the charges on u and d?

A)
B)
C)
D)

Question 67

Baryons are composed of 3 quarks.If all 3-quark compositions of particles could happen,what would be the highest possible charge for such a particle?

A)1 e
B)2 e
C)3 e
D)There is no upper limit,though the charge is usually less than 3e.

Question 68

What following quantity is conserved in the following reaction:
?

A)charge
B)lepton number
C)baryon number
D)All of the above.

Question 69

Which of the following particles is made of two or more smaller particles?

A)electron
B)photon
C)proton
D)None of the above.

Question 70

Experimentally,strange particles can be produced in abundance,but they decay relatively slowly.This occurs because strangeness

A)is conserved in both their production and decay.
B)is conserved in their production but not in their decay.
C)is conserved in their decay but not in their production.
D)is not conserved in either their production or their decay.

Question 71

If two quarks in an anti-proton have the color anti-red and anti-blue,the third quark must have the color

A)red.
B)blue.
C)anti-purple.
D)anti-green.

Question 72

The charge of some quarks or anti-quarks is

A)0.
B) · (1.6 × 10−¹⁹)C.
C) · (1.6 × 10−¹⁹)C.
D)1 · (1.6 × 10−¹⁹)C.

Question 73

According to the standard model,a quark and its antiquark may have the same

A)spin.
B)baryon number.
C)charge.
D)All of the above may be the same.

Question 74

Mesons are composed of ________ quarks,and baryons are composed of ________ quarks.

A)two,two
B)two,three
C)three,two
D)three,three

Question 75

If a K⁰ meson at rest decays in 0.80 × 10−¹⁰ s,how far will a K⁰ meson moving at 0.96c travel through a bubble chamber? (c​ = 3.00 × 10⁸ m/s)

A)8.2E-2 m
B)2.3E-2 m
C)6.5E-3 m
D)1.2E-1 m
E)​4.6E-3 m

Question 76

Mesons are always composed of

A)two quarks,one being classified as a quark and the other as an antiquark.
B)a quark of one color and an antiquark of the anticolor.
C)an up or down quark and a down or up antiquark.
D)Two of the above choices are correct.

Question 77

The strangeness of an anti-proton is

A)+1.
B)0.
C)-1.
D)-2.

Question 78

When considering the law of conservation of lepton number for a reaction,how many different lepton numbers must be checked?

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

Question 79

Of the quarks u,d,c,s,t,and b,which have positive fractional electronic charge?

A)u,d,c
B)d,s,b
C)s,t,b
D)u,c,t

Question 80

The law of conservation of strangeness tells us that strangeness is not conserved for which of the following interactions?

A)strong
B)electromagnetic
C)weak
D)All three of the above interactions conserve strangeness.