Deck 34: Nuclear Fission and Fusion

Question 1

Nuclear reactors that produce consumer power in present times are powered by

A)fission.
B)fusion.
C)both fission and fusion.

Answer 1

fission.

Question 2

A sphere of pure U-235 will explode if it is

A)hot enough.
B)shaken hard enough.
C)big enough.
D)none of the above

Answer 2

big enough.

Question 3

When a lump of uranium is broken into smaller pieces, the total surface area

A)decreases.
B)remains the same.
C)increases.

Answer 3

increases.

Question 4

Electrical forces inside a nucleus contribute to nuclear

A)stability.
B)instability.
C)both of these
D)neither of these

Question 5

In gaseous form at the same temperature, the average speed of U-238 compared to the speed of U-235 is

A)less.
B)more.
C)the same.

Question 6

Which will leak more neutrons?

A)two separate lumps of uranium.
B)the same two lumps stuck together.
C)both the same

Question 7

When two pieces of fissionable material are assembled, the average distance that a neutron travels before escaping will

A)decrease.
B)increase.
C)be the same.

Question 8

The idea in fission-bomb design is to

A)form a supercritical mass from one or more subcritical masses.
B)bring neutrons and subcritical uranium together.
C)both of these
D)neither of these

Question 9

In the fissioning of uranium, a chain reaction is caused by

A)the kinetic energy of the decay products.
B)ejected neutrons.
C)alpha particles.
D)none of the above

Question 10

If a critical mass of fissionable material in a spherical shape is flattened like a hamburger, it will be

A)supercritical.
B)subcritical.
C)as critical.

Question 11

A nuclear power plant is very similar to

A)nuclear bombs, but with more control.
B)any conventional power plant, but with uranium as fuel.
C)a photovoltaic solar cell power plant.
D)all of the above
E)none of the above

Question 12

Compared with the mass of a uranium nucleus before splitting, the split fragments have

A)less mass.
B)the same mass.
C)more mass.

Question 13

The term critical mass refers to the least amount of mass that can

A)sustain a chain reaction.
B)squelch a chain reaction.
C)explode when rapidly brought against a neighboring piece.
D)none of the above

Question 14

The conversion of mass to energy of other forms via nuclear fission is

A)less than 1%.
B)about 10%.
C)about 20%.
D)about 30%.
E)more than 30%.

Question 15

Which has the smaller critical mass; U-235 that releases 2.5 neutrons per fission, or Pu-239 that releases 2.7 neutrons per fission?

A)U-235
B)Pu-239
C)both would have the same critical mass.

Question 16

The kinetic energy of fission fragments in a nuclear reactor

A)superheats water and produces steam.
B)converts to gamma-ray radiation.
C)becomes radioactive pollution.
D)converts directly to electricity.
E)none of the above

Question 17

Compared with protons, neutrons are more effective nuclear bullets in nuclear reactions since they have

A)slightly greater mass than a proton.
B)no charge.
C)a wider cross-section than a proton.
D)all of the above
E)none of the above

Question 18

The balance between electrical and nuclear strong forces is more tenuous in

A)light elements.
B)middle size elements like iron.
C)heavier elements.
D)all of the above
E)none of the above

Question 19

Uranium-235, uranium-238 and uranium-239 are different

A)elements.
B)ions of the same element.
C)isotopes of the same element.
D)none of the above

Question 20

A chain reaction progresses when the average number of liberated neutrons that cause further fissions is

A)zero.
B)less than one.
C)one or more.
D)none of the above

Question 21

U-235 and Pu-239 are both

A)radioactive isotopes.
B)fissionable isotopes.
C)heavier than lead.
D)all of the above
E)none of the above

Question 22

A neutron bouncing off a heavy nucleus loses speed. If it instead bounces off a light nucleus it loses

A)less speed.
B)more speed.
C)the same amount of speed.

Question 23

Carbon was used in Fermi's first nuclear reactor to

A)slow neutrons.
B)increase the speed of neutrons.
C)absorb neutrons.
D)none of the above

Question 24

When a nucleus of U-238 absorbs a neutron and becomes U-239, a beta emission, then another beta emission results in

A)Th-239.
B)Pa-239.
C)U-235.
D)Pu-239.
E)Pb-206.

Question 25

The possible fate of a neutron in ordinary uranium metal is to

A)cause fission of U-235 if present.
B)escape the metal.
C)be absorbed by U-238 without causing fission.
D)all of the above
E)none of the above

Question 26

Compared with a neutron bouncing off a carbon nucleus, a neutron bouncing off an iron nucleus loses

A)less speed.
B)more speed.
C)the same amount of speed.

Question 27

The energy output of a typical nuclear reactor is via

A)heating water to form steam.
B)directing steam to a turbine.
C)spinning a turbine to generate electricity.
D)all of the above
E)none of the above

Question 28

What does a breeder reactor "breed?"

A)more energy output than energy input
B)fissionable isotopes from a non-fissionable isotopes
C)more mass than it begins with
D)all of the above
E)none of the above

Question 29

Plutonium is extremely rare in natural ore deposits because it

A)is artificially created.
B)is chemically inert.
C)is a gas at room temperature.
D)has a tiny half-life compared with the age of Earth.
E)none of the above

Question 30

The water that operates a fission-reactor turbine is

A)not the same water that flows through the reactor.
B)heated to high-pressure steam.
C)without radioactivity.
D)all of the above
E)none of the above

Question 31

Control is maintained in a nuclear reactor by control rods that

A)absorb excess neutrons.
B)emit fast neutrons.
C)both of these
D)neither of these

Question 32

Neutrons that will initiate the fission of U-235 require speeds that are

A)less than average.
B)about average.
C)more than average.
D)all of the above
E)none of the above

Question 33

Reactions that take place in a breeder reactor change

A)elements into different elements.
B)molecules into different molecules.
C)ions into different ions.
D)all of the above
E)none of the above

Question 34

If all the uranium in the world were exhausted, breeder reactors would be

A)in greater demand.
B)relics of a brief age.
C)both of these
D)neither of these

Question 35

A neutron will more likely slow in speed if it bounces from a

A)light-weight nucleus.
B)nucleus of moderate mass.
C)heavy nucleus.
D)none of the above

Question 36

Plutonium is radioactively toxic

A)in any form.
B)although less toxic than radium.
C)both of these
D)neither of these

Question 37

Two isotopes that undergo nuclear fission are

A)U-235 and Pu-239.
B)Th-238 and U-235.
C)all of these
D)none of these

Question 38

Although plutonium alone is chemically toxic, it is not toxic when

A)oxidized.
B)ionized.
C)subcritical.
D)none of the above

Question 39

The function of graphite in the first atomic reactor was to

A)slow fast neutrons.
B)emit fast neutrons.
C)moderate uranium isotopes.
D)none of the above

Question 40

When neptunium emits a beta particle the result is

A)a different isotope of neptunium.
B)uranium.
C)plutonium.
D)lead.
E)none of the above

Question 41

Which of these nuclei has the least mass?

A)hydrogen
B)iron
C)lead
D)uranium
E)all the same

Question 42

The fact that more radioactive particles are spewed from coal-fired power plants than nuclear fission reactors is evidence that

A)coal is more radioactive than uranium.
B)coal-fired plants have less shielding.
C)coal-fired plants are more numerous.
D)all of the above
E)none of the above

Question 43

A mass spectrometer separates

A)ions of different elements.
B)different-mass ions of the same element.
C)different-mass ions of the same speed.
D)all of the above
E)none of the above

Question 44

The nuclear process having by-products with least radioactivity is

A)fission.
B)fusion.
C)about the same for both.

Question 45

Various singly-ionized atomic nuclei of the same speed are directed into a magnetic field in a mass spectrometer where they are deflected and strike a detecting screen. The particles most strongly deflected are those of

A)least mass.
B)greatest mass.
C)same for all

Question 46

What is the central equation of mass-energy equivalence?

A)W = Fd
B)KE = ½ mv²
C)m = F/a
D)E = mc²

Question 47

Relative to a fossil-fuel plant, a nuclear power plant produces

A)more electricity.
B)less heat and smoke.
C)less pollution.
D)all of the above
E)none of the above

Question 48

The energy released in both fission and fusion is mainly in the form of

A)kinetic energy of fragments.
B)alpha radiation.
C)beta radiation.
D)gamma radiation.
E)none of the above

Question 49

The disadvantages to fission power plants include

A)radioactive waste disposal.
B)production of plutonium for possible weapons proliferation.
C)risk of accidental release of radioactivity.
D)all of the above
E)none of the above

Question 50

To pluck a nucleon from a nucleus requires

A)work.
B)kinetic energy.
C)potential energy.
D)none of the above

Question 51

The nucleus that has the least mass per nucleon is

A)hydrogen.
B)iron.
C)lead.
D)uranium.
E)plutonium.

Question 52

The nucleus that has the greatest mass per nucleon is

A)hydrogen.
B)iron.
C)lead.
D)uranium.
E)plutonium.

Question 53

The percentage of electricity from nuclear power generated in recent decades in the United States has been about

A)10%.
B)20%.
C)30%.
D)40%.
E)more than 40%

Question 54

Compared with the sum of isolated-nucleon masses, their collective mass in a composite nucleus is

A)more.
B)less.
C)the same.

Question 55

The products of nuclear fission are radioactive due to their

A)combustive natures.
B)capacity to hold vast amounts of energy.
C)greater neutron to proton ratio compared with stable nuclei in the same mass range.
D)short half-lives.
E)none of the above

Question 56

Fissioning a lead nucleus would yield a net

A)absorption of energy.
B)release of energy.
C)neither of these

Question 57

An important feature of the mass spectrometer is that

A)all ions enter the device at equal speeds.
B)ions of different masses bend differently.
C)the greater an ion's mass, the wider its circular arc.
D)a magnetic field exerts forces on moving charged particles.
E)all of the above

Question 58

Energy released by the Sun results from the process wherein atomic nuclei

A)break apart.
B)combine.
C)both of these
D)neither of these

Question 59

A nucleon has more mass on average when it is

A)inside the nucleus.
B)removed from the nucleus.
C)both the same

Question 60

The nucleus having the most tightly bound nucleons is

A)hydrogen.
B)iron.
C)lead.
D)uranium.
E)plutonium.

Question 61

When two light atoms fuse together, mass

A)converts to kinetic energy.
B)converts to high-energy gamma radiation.
C)is created from energy of other forms.
D)is gained.

Question 62

Fissioning an iron nucleus would occur with

A)absorption of energy.
B)release of energy.
C)neither absorption nor release of energy

Question 63

Fusing two iron nuclei would occur with

A)absorption of energy.
B)release of energy.
C)neither of these

Question 64

An element is changed into a completely different element in

A)radioactive alpha decay.
B)radioactive beta decay.
C)nuclear fission.
D)nuclear fusion.
E)all of the above

Question 65

Between the processes of nuclear fission and fusion, radioactive by-products are more characteristic of nuclear

A)fission.
B)fusion.
C)both of these
D)neither of these

Question 66

Compared with the energy produced by fissioning a gram of uranium, the energy produced by fusing a gram of deuterium is

A)more.
B)less.
C)the same.

Question 67

Iron is a poor choice of nuclear fuel because it releases

A)energy only when fused.
B)energy only when fissioned.
C)no energy when fused or fissioned.

Question 68

Detonation of a fission-type uranium bomb begins by

A)splitting uranium.
B)pressing together pieces of uranium.
C)igniting a small conventional bomb.
D)all of the above
E)none of the above

Question 69

Deuterium and tritium are both

A)forms of hydrogen.
B)isotopes of the same element.
C)both of these
D)neither of these

Question 70

In both fission and fusion, mass

A)is created from energy of other forms.
B)converts to kinetic energy.
C)converts to gamma radiation.
D)remains the same.

Question 71

Early 21^st Century research in nuclear fusion uses

A)laser beams.
B)ultra-hot plasmas.
C)both of these
D)neither of these

Question 72

If gold were used as nuclear fuel, it would be best

A)fused.
B)fissioned.
C)either of these

Question 73

According to the "energy valley" of the mass-per-nucleon versus atomic-number graph, the element with the least mass per nucleon is

A)hydrogen.
B)helium.
C)iron.
D)uranium.
E)none of the above

Question 74

If oxygen were used as nuclear fuel, it would be best

A)fused.
B)fissioned.
C)either of these

Question 75

In both fission of uranium and fusion of hydrogen, mass

A)decreases.
B)remains constant.
C)increases.

Question 76

Fusing two carbon nuclei would occur with

A)absorption of energy.
B)release of energy.
C)neither of these

Question 77

When U-235 undergoes fission, the total number of protons in the fragments is

A)90.
B)91.
C)92.
D)93.
E)none of the above

Question 78

Detonation of a fusion-type hydrogen bomb begins by

A)splitting uranium.
B)pressing together pieces of uranium.
C)igniting a fission bomb.
D)all of the above
E)none of the above

Question 79

Fissioning carbon would occur with

A)absorption of energy.
B)release of energy.
C)neither of these

Question 80

Sustained energy output by fusion is a daily occurrence in

A)military installations.
B)breeder reactors.
C)the Sun.
D)Earth's interior.