Deck 30: Nuclear Energy and Elementary Particles

Question 1

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.

Answer 1

decelerated.

Question 2

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

Answer 2

low velocity neutron

Question 3

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 3

negative beta decay

Question 4

Nuclear fission was first observed by:

A)Hahn and Strassman.
B)Meitner and Frisch.
C)Einstein and Fermi.
D)Dirac and Heisenberg.

Question 5

The water surrounding the fuel rods in a nuclear fission reactor serves what purpose(s)?

A)coolant
B)moderator
C)Both choices above are valid.
D)None of the choices above are valid.

Question 6

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 7

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 8

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 9

Where is the largest untapped source of uranium?

A)Canada
B)Siberia
C)Africa
D)none of the above

Question 10

Assume that (i)the energy released per fission event of ²³⁵U is 208 MeV,and (ii)30% 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 one GW electrical power output of a typical power plant? (1 eV = 1.6 x 10^-19 J)

A)2 x 10¹⁶ fission/s
B)1 x 10²⁰ fission/s
C)3 x 10²⁴ fission/s
D)2 x 10²⁷ fission/s

Question 11

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 12

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

Question 13

In a nuclear reactor which uses the fission process,which of the following is the most likely result in the event of a cooling system failure followed by a nuclear accident?

A)proliferation of plutonium fuel
B)accumulation of critical mass of fissionable material
C)spread of radioactive material into the environment
D)reduction of ozone in upper atmosphere

Question 14

Which of the following can only occur if the reproduction constant,K,exceeds 1?

A)nuclear meltdown at a nuclear power plant
B)explosive release of radioactivity and steam from a nuclear power plant
C)the explosion of a nuclear bomb
D)All of the above require that K exceed 1.

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

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

A)1.2 x 10⁵ kW*h
B)7.7 x 10⁶ kW*h
C)11 x 10⁶ kW*h
D)22 x 10⁶ kW*h

Question 17

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 18

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

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

Question 19

In a nuclear fission process involving the use of ²³⁹Pu fuel,if the approximate average binding energy per nucleon in the product fragments is 8.5 MeV while that of the fuel atom is 7.7 MeV,what approximate net energy is released per fission?

A)190 MeV
B)240 MeV
C)2 000 MeV
D)3 800 MeV

Question 20

What characteristic is preferred in the elements contained in moderator materials when used in a nuclear fission reactor?

A)low atomic mass
B)metallic
C)non-metallic
D)high atomic mass

Question 21

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 22

The reason that a thermonuclear fusion reaction cannot be maintained in the oceans of the earth is because:

A)the temperature is not high enough.
B)the density is not high enough.
C)there is insufficient deuterium in the ocean.
D)the deuterium in the ocean is not radioactive.

Question 23

How much kinetic energy must a deuterium ion (charge = 1.6 x 10^-19 C)have to approach within 1.0 x 10^-14 m of another deuterium ion? (k_e =8.99 x 10⁹ N*m²/C² and 1 keV = 1.6 x 10^-16 J)

A)30 keV
B)50 keV
C)70 keV
D)140 keV

Question 24

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 25

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 26

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 27

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 28

How fast is an ion of deuterium moving,assuming rms speed,if it is in a plasma with a temperature of 100 x 10⁶ K? (k_B = 1.38 x 10^-23 J/K and m_D = 2 x 1.66 x 10^-27 kg)

A)1.12 x 10⁶ m/s
B)0.93 x 10⁵ m/s
C)0.46 x 10⁵ m/s
D)2.32 x 10⁴ m/s

Question 29

The formation of a star requires the consideration of the effects of gravity and the energy from nuclear reactions and a star will form only when both the temperature and density are sufficiently high.In the birth of a star:

A)gravity produces the initial required high temperature and density.
B)nuclear reactions produce the initial high temperature.
C)nuclear reactions produce the initial required high density.
D)nuclear reactions produce the initial required high temperature and density.

Question 30

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 31

Which particle in the free state is least stable?

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

Question 32

In the proton-proton cycle,the eventual product is:

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

Question 33

One in 6 500 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 x 10^-13 J,r_water = 10³ kg/m³,one mole of water has a mass of 18 g,and N_A = 6.02 x 10²³)

A)8.0 x 10¹⁰ J
B)9.6 x 10¹⁰ J
C)4.8 x 10¹¹ J
D)1.5 x 10¹² J

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

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 36

Which of the following particles has not been observed experimentally?

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

Question 37

Which of the following forces is the weakest?

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

Question 38

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 39

Assuming the Lawson criterion for the deuterium-tritium interaction, ,what is the minimum plasma ion density at 10⁸ K?

A)10⁶/cm³
B)10²²/cm³
C)10^-6/cm³
D)More information is needed.

Question 40

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 41

A positron and an electron differ in:

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

Question 42

"MeV/c²" is a unit for:

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

Question 43

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 44

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 45

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 46

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 47

Calculate the range of the force that might be produced by the virtual exchange of a proton.Assume DE*Dt = h/2p.(m_p = 1.67 x 10^-27 kg,c = 3.00 x 10⁸ m/s,and h/2p = 1.05 x 10^-34 J*s)

A)6.7 x 10^-25 m
B)2.1 x 10^-16 m
C)6.0 x 10^-8 m
D)1.5 x 10^-15 m

Question 48

What quantity is conserved in the following reaction?

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

Question 49

The pion (m_p = 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 DE*Dt = h/2p? (h/2p = 1.05 x 10^-34 J*s,c = 3.00 x 10⁸ m/s,and 1 eV = 1.6 x 10^-19 J)

A)1.2 x 10^-15 m
B)1.4 x 10^-15 m
C)2.0 x 10^-15 m
D)7.5 x 10^-15 m

Question 50

Which particle was the last to be discovered?

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

Question 51

Which of these particles has the most mass?

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

Question 52

The medical diagnostic technique PET stands for:

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

Question 53

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 54

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 55

If protons have a half-life of 10³¹ years,what fraction of the original protons have decayed during the 10¹⁰ year existence of the universe?

A)10/31
B)21/31
C)5 x 10^-7
D)less than any of the above values

Question 56

In the decay of the muon into an electron,a neutrino,and an antineutrino,the antineutrino is a(n)________ antineutrino.

A)electron
B)muon
C)tau
D)gluon

Question 57

A neutron and a proton have the same:

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

Question 58

The attractive force between protons and neutrons in the nucleus is brought about by the exchange of a virtual pi-meson (m_p = 140 MeV/c²).Estimate the longest time a p can exist in accordance with the uncertainty principle DE*Dt = h/2p.(h/2p = 1.05 x 10^-34 J*s,1 eV = 1.6 x 10^-19 C)

A)3.3 x 10^-18 s
B)2.4 x 10^-21 s
C)4.7 x 10^-24 s
D)6.9 x 10^-27 s

Question 59

Which of the following is not true of electron neutrinos?

A)They are spinless.
B)They are chargeless.
C)They are massless (or nearly so).
D)They are leptons.

Question 60

What quantity is conserved in the following reaction?

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

Question 61

The spin of all quarks is:

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

Question 62

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 63

If a K⁰ meson at rest decays in 0.90 x 10^-10 s,how far will a K⁰ meson moving at 0.96 c travel through a bubble chamber? (c = 3.00 x 10⁸ m/s)

A)9.3 cm
B)1.1 cm
C)53 cm
D)42 cm

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

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 66

The S⁺,S⁰,and S^- all have strangeness of (-1).The collision of a proton and a neutron to produce a S⁰ and an anti-S^- cannot occur because it does not conserve:

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

Question 67

Which of the following decays violates conservation of lepton number?

A)
B)
C)
D)

Question 68

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

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

Question 69

Which of the following is not conserved?

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

Question 70

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 71

Which of the following particle reactions can occur?

A)
B)
C)
D)

Question 72

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 73

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 74

The following reaction can occur by the strong interaction: p⁰ + n ® K⁺ + S^-.If the quark composition of the n is (udd),the p⁰ is and the composition of the K⁺ is ,what is the quark composition of the S^-?

A)dds
B)uds
C)sss
D)

Question 75

Which of the following particle reactions cannot occur?

A)
B)
C)
D)

Question 76

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 77

A proton and antiproton each with total energy 400 GeV collide head-on.What is the total energy (particles + energy)released?

A)800 GeV
B)400 GeV
C)zero
D)1 600 GeV

Question 78

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 79

The strangeness of an anti-proton is:

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

Question 80

The S⁺,S⁰,and S^- all have strangeness of (-1).The collision of an anti-proton and a neutron may produce which of the following particles?

A)S^- and S⁰
B)S⁺ and anti-S⁰
C)anti-S⁺ and S⁰
D)anti-S^- and S⁰