Deck 15: Fusion and Fission: and a New Energy

Question 1

In the nuclear reaction ¹H + ²H ·³He, how does the nuclear energy and the total rest- mass of the two hydrogen nuclei compare with the nuclear energy and the total rest- mass of the resulting helium nucleus?

A) Nuclear energy of helium is more, mass of helium is the same as the mass of the two hydrogen nuclei.
B) Nuclear energy of helium is more, mass of helium is more.
C) Nuclear energy of helium is less, mass of helium is the same as the mass of the two hydrogen nuclei.
D) Nuclear energy of helium, and mass of helium, are both the same as the nuclear energy and the mass of the two hydrogen nuclei.
E) Nuclear energy of helium is less, mass of helium is less.

Answer 1

Nuclear energy of helium is less, mass of helium is less.

Question 2

Suppose that you fission a sulfur nucleus, ³² S, into two fragments. Referring to the graph above, does this process convert nuclear energy to other forms, or is it vice versa?

A) Nuclear energy to other forms, because this process proceeds downward, from higher to lower energy on the curve.
B) Other forms to nuclear energy, because this process proceeds upward, from lower to higher energy on the curve.
C) Other forms to nuclear energy, because this process proceeds downward, from higher to lower energy on the curve.
D) Nuclear energy to other forms, because this process proceeds upward, from lower to higher energy on the curve.
E) This is definitely the wrong answer; go back and start over.

Answer 2

Other forms to nuclear energy, because this process proceeds upward, from lower to higher energy on the curve.

Question 3

According to the nuclear energy curve, would fusion or fission or neither release nuclear energy from carbon [atomic number 6], and why?

A) Neither, because all other elements have higher nuclear energies.
B) Fusion, because then the reaction product has a lower atomic number and a higher nuclear energy.
C) Fission, because then the reaction products have higher atomic numbers and a lower nuclear energy.
D) Fission, because then the reaction products have lower atomic numbers and a higher nuclear energy.
E) Fusion, because then the reaction product has a higher atomic number and a lower nuclear energy.

Answer 3

Fusion, because then the reaction product has a higher atomic number and a lower nuclear energy.

Question 4

Nuclear fusion is a process in which

A) a heavy nucleus is split into two or more lighter nuclei.
B) a small particle is spontaneously emitted from a nucleus.
C) two or more light nuclei are combined into a single heavier nucleus.
D) atoms combine into molecules.
E) None of the above.

Question 5

The fusion of ⁶ Li and ¹⁰ N results in creation of 3 5

A) "¹⁶ O and no energy transformed to other forms."
B) "¹⁶ O and energy transformed to other forms."
C) "⁴ He and energy transformed to other forms."
D) "⁴ He and no energy transformed to other forms."
E) "salami and cheese sandwiches."

Question 6

Fusion is often called a "thermonuclear reaction" because

A) it is a nuclear reaction that is self- sustaining a sufficiently high temperatures.
B) it produces nuclear energy.
C) it is a process that converts thermal energy into nuclear energy.
D) it is a nuclear reaction that consumes, or uses, more thermal energy than it creates.
E) it is a nuclear reaction that produces more total energy than it consumes.

Question 7

Has a nuclear device ever been exploded by a terrorist?

A) No, although a terrorist has been arrested who possessed and planned to use a stolen nuclear weapon.
B) No, although a terrorist has been arrested who possessed and planned to use a dirty bomb.
C) No, in fact there are no known instances of terrorists even possessing a nuclear device.
D) Yes, a small dirty bomb was exploded during the Iraq War.
E) Yes, terrorists have entered a nuclear power plant in Pakistan and dispersed radioactive materials.

Question 8

Centrifuge separation, a method of separating ²³⁵U from ²³⁸U, works because of

A) the difference in the masses of the two nuclei.
B) the fact that both these nuclei are radioactive.
C) the difference in electrical charge of the two nuclei.
D) the difference in size of the two nuclei.
E) the fact that both these nuclei respond to (or feel) the strong nuclear force.

Question 9

Other than radioactive decay, how can energy be released from the nucleus?

A) Nuclear fusion.
B) Nuclear fission.
C) Both of the above.
D) Thermal decay.
E) All of the above.

Question 10

Which of the following works best for fusing hydrogen?

A) Bring the hydrogen nuclei together very slowly until they hold together.
B) Heat it up to such a high temperature that collisions cause the nuclei to fuse.
C) Hit the hydrogen nucleus with a neutron.
D) Hit the hydrogen nucleus with an electron.
E) Cool the hydrogen until the nuclei are at rest and then suddenly compress them.

Question 11

Lise Meitner was

A) one of the discoverers of nuclear fission.
B) one of the discoverers of radioactivity.
C) one of the discoverers of nuclear fusion.
D) a leader in developing the world's first nuclear reactor.
E) discoverer of the ozone hole over the southern polar region.

Question 12

When ¹H and ²H fuse, the result is

A) a particle with a mass less than the sum of the mass of ¹H plus the mass of ²H.
B) a particle with a mass equal to the sum of the mass of ¹H plus the mass of ²H.
C) crabgrass.
D) a particle with a mass greater than the sum of the mass of ¹H plus the mass of ²H.
E) the annihilation of both nuclei and the production of energy in the form of radiation.

Question 13

The astronomical phenomenon that created the elements heavier than iron is

A) neutron stars.
B) the collapse of a star to a white dwarf.
C) supernova explosions.
D) black holes.
E) the birth [or formation] of stars.

Question 14

When a hydrogen bomb explodes, hydrogen fuses to form helium. According to Einstein's mass- energy equivalence [that is, according to E=mc²], does this result in an change in the total mass of the material?

A) Yes, the mass increases, but by such a small amount that it would be impossible to measure it.
B) Yes, the mass decreases, and by a measurable amount.
C) Yes, the mass increases, and by a measurable amount.
D) Yes, the mass decreases, but by such a small amount that it would be impossible to measure it.
E) No, the mass remains exactly the same.

Question 15

In order for a substance to sustain a fission chain reaction, one important condition is that

A) the nuclei must collide with enough energy to overcome the electrical repulsion between them.
B) energy must be continually supplied from the outside.
C) each fissioning nucleus must release a sufficient number of alpha- particles.
D) each fissioning nucleus must release a sufficient number of neutrons.
E) the nuclei must stay in shape by maintaining a regular jogging program.

Question 16

Which of the following works best for fissioning a uranium nucleus?

A) Heat it up to such a high temperature that collisions cause uranium nuclei to split.
B) Hit it with a neutron.
C) Hit it with a proton.
D) Hit it with another uranium nucleus.
E) Hit it with an electron.

Question 17

In a fusion bomb, what initiates, or triggers, the fusion reaction?

A) nuclear magnetic resonance
B) a laser beam
C) a sudden release of neutrons
D) a fission explosion
E) conventional chemical explosive, designed to implode instead of explode

Question 18

A "critical mass" is needed for a chain reaction because

A) if the mass is too small the temperature achieved during fission will be too low to sustain the reaction.
B) if the mass is too small, there will not be enough uranium to start the reaction.
C) if the mass is too large, the temperature will get too high and the entire mass will blow up without fissioning.
D) if the mass is too large, the density will be too high to sustain a chain reaction.
E) if the mass is too small, too many neutrons will leak out without causing fission.

Question 19

In one popular type of fusion reaction, ²H fuses with ³H to yield ⁴He and

A) a neutron.
B) an alpha particle.
C) a beta particle.
D) a proton.
E) Actually no other particle is produced.

Question 20

One nuclear reaction that occurs occasionally in the sun is the fusion of three alpha particles. What isotope is produced by this reaction? NOTE: Atomic number 6 is carbon, number 7 is nitrogen, and number 8 is oxygen.

A) 14_N
B) 12_O
C) 14_C
D) 12_C
E) 12_N

Question 21

The source of energy for the Hiroshima bomb was basically the same as the source of energy for

A) hydro- electric plants.
B) future fusion reactors.
C) the sun.
D) nuclear power reactors.
E) other chemical reactions.

Question 22

The United States originally started the fission bomb project because

A) it was afraid that Germany was developing it.
B) its military wanted the biggest bomb possible.
C) it seemed like it would be fun.
D) it thought it would need it against Japan.
E) it wanted to threaten Russia with it after the war.

Question 23

What is the source of the energy for the creation of heavy elements [heavier than iron]?

A) Fission.
B) Hydrogen fusion.
C) Helium fusion.
D) Gravitational collapse.
E) The shock of a supernova explosion.

Question 24

Recalling that iron lies at the lowest point of the "nuclear energy curve," which of the following nuclear reactions would "release" [that is, convert to other forms] nuclear energy from iron?

A) Fission
B) Fusion
C) Both of the above.
D) None of the above.
E) This is the wrong answer.

Question 25

The A- bomb is based on

A) nuclear fission.
B) a chemical reaction.
C) nuclear fusion.
D) popcorn.
E) radioactive decay.

Question 26

The naturally- occurring isotope that will sustain a fission chain reaction is

A) 238_U.
B) 235_U.
C) 239_Pu.
D) 14_C.
E) tritium, i.e., ³H.

Question 27

The fission reaction involves

A) the splitting of a large molecule into smaller molecules.
B) the combining of two low- mass nuclei.
C) the splitting of a heavy nucleus.
D) the combining of two lighter molecules into a heavier molecule.
E) the splitting of a light nucleus.

Question 28

The four plausible routes by which terrorists might use nuclear devices include

A) obtaining weapons- grade uranium or plutonium and building a nuclear weapon from it.
B) seizing an intact nuclear weapon.
C) Both of the above.
D) sabotaging a nuclear power plant.
E) All of the above.

Question 29

The sun's energy comes from

A) the fission of helium into hydrogen.
B) the fission of uranium.
C) the fusion of helium into hydrogen.
D) the fusion of hydrogen into helium.
E) None of the above.

Question 30

The term "dirty bomb" refers to

A) a bomb that uses conventional explosive to disperse radioactive materials.
B) any nuclear device that is used for terrorist purposes.
C) a conventional chemical bomb that disperses pieces of metal in order to harm the maximum number of people.
D) a nuclear device that releases neutrons in order to kill people without harming buildings and other structures.
E) a nuclear device that is optimized for the release of radioactive materials.

Question 31

Except for hydrogen, helium, and a little lithium, the lower- mass elements (lighter than iron) that are spread throughout the dust of the universe were created

A) in the original creation of the universe.
B) during the fusion process that powers the stars, and then released in supernova explosions.
C) in Kansas.
D) during the shock of a supernova explosion.
E) in hot white dwarf stars.

Question 32

The first laboratory discovery of nuclear fission occurred

A) in London in 1930.
B) in Germany in 1938.
C) in the United States in 1940.
D) in New Mexico in 1944
E) in Marie Curie's lab in the early 1900s.

Question 33

Regarding the size, or total megatonnage, of a hydrogen bomb:

A) It is limited to about 10 megatons by the fact that tritium has a short half- life and thus must react very quickly.
B) It is unlimited, because there is no limit to the amount of fusible material that can be put together.
C) It is unlimited, because there is no limit to the amount of chain- reacting material that can be put together.
D) It is limited, because of the existence of a "critical mass" for fusion, to about one megaton.
E) It is limited, because of the existence of a "critical mass" for fusion, to about 20 kilotons.

Question 34

Most of the hydrogen bomb's energy comes from

A) fission.
B) fusion.
C) a chemical reaction.
D) magic.
E) radioactive decay.

Question 35

The element iron, having atomic number 26, is the "crossover point" between fusion and fission. Why?

A) Because all elements heavier than iron are radioactive, implying that they will fission easier than they will fuse.
B) Because for elements lighter than iron, fusion converts nuclear energy to non- nuclear energy, whereas for elements heavier than iron, fission converts nuclear energy to non- nuclear energy.
C) Because for elements lighter than iron, fusion converts non- nuclear energy to nuclear energy, whereas for elements heavier than iron, fission converts non- nuclear energy to nuclear energy.
D) Because neutrons will only split the elements that are heavier than iron.
E) Because of the neutron balance that results from splitting a nucleus.

Question 36

In a fission reaction, such as occurs in a nuclear power plant,

A) nuclear energy is converted to thermal energy and other forms of energy.
B) energy is created.
C) nuclear energy is created.
D) thermal energy and other forms of energy are converted to nuclear energy.
E) heat is converted to work.

Question 37

According to the nuclear energy curve shown in the graph above, nuclear energy can be transformed to other forms by

A) fusing nuclei heavier than iron.
B) fusing nuclei lighter than iron.
C) fissioning nuclei lighter than iron.
D) ironing your clothes.
E) fissioning any nuclei including iron.

Question 38

The nuclear energy curve shown in the graph above tells us that iron is

A) the most stable nucleus, because the least work is needed to pull it apart into separate particles.
B) the most stable nucleus, because the most work is needed to pull it apart into separate particles.
C) the least stable nucleus, because the least work is needed to pull it apart into separate particles.
D) good to eat.
E) the least stable nucleus, because the most work is needed to pull it apart into separate particles.

Question 39

The two nuclei used for the fuel in fission bombs are

A) "235_{Th and} 235_U."
B) "²³⁴Th and ²³⁹Pu."
C) "235_{U and} 239_Pu."
D) "238_{U and} 239_Pu."
E) "234_{Th and} 238_U."

Question 40

In fission bombs, a certain "critical mass" is needed because

A) the fissionable material will not reach a sufficiently high temperature unless this much material is present.
B) too small an amount of uranium will not hold together throughout the reaction, and thus the uranium falls apart and the reaction goes out before it is completed.
C) for smaller masses the pressure is so low that neutrons move too slowly through the uranium to sustain a chain reaction.
D) if the mass is too small, too many neutrons pass through the uranium and out the sides without hitting a nucleus.
E) it is impossible to fission a uranium nucleus unless it is near a large number of other uranium nuclei.

Question 41

The source of the sun's energy is

A) gravitational energy.
B) nuclear fusion.
C) nuclear fission.
D) granola bars.
E) chemical reactions.

Question 42

According to the nuclear energy curve, would fusion or fission or neither release nuclear energy from gold [atomic number 79], and why?

A) Fusion, because then the reaction product has a lower atomic number and thus a higher nuclear energy.
B) Neither, because all other elements have higher nuclear energies than carbon.
C) Fission, because then the reaction products have lower atomic numbers and thus a lower nuclear energy.
D) Fusion, because then the reaction product has a higher atomic number and thus a lower nuclear energy.
E) Fission, because then the reaction products have higher atomic numbers and thus a higher nuclear energy.

Question 43

A neutron makes a better "nuclear bullet", for fissioning a nucleus, than does a proton. This is because

A) it is easy to accelerate neutrons to high speeds in nuclear accelerators.
B) the negative charge on the neutron attracts it to the nucleus.
C) unlike the proton, the neutron is not repelled by the charge on the nucleus.
D) protons do not feel the strong nuclear force and thus do not interact appreciably with the nucleus.
E) neutrons are so much more massive than protons.

Question 44

In which of the following nuclear processes are other forms of energy converted into nuclear energy? In other words, in which of these processes is nuclear energy created?

A) Exothermic ["heat producing"] chemical reactions.
B) Endothermic ["heat consuming"] chemical reactions.
C) In nuclear fission of the lighter elements and nuclear fusion of the heavier elements.
D) In nuclear fusion of the lighter elements and nuclear fission of the heavier elements.
E) Supernova explosions, i.e., explosions of stars.

Question 45

The four plausible routes by which terrorists might use nuclear devices do not include

A) seizing an intact nuclear weapon.
B) sabotaging a nuclear power plant.
C) enriching natural uranium to weapons grade uranium, and building a nuclear weapon from it.
D) acquiring radioactive material and using conventional explosive to disperse this material.
E) obtaining weapons- grade uranium or plutonium and building a nuclear weapon from it.

Question 46

All fission bombs are based on

A) either uranium or plutonium or both.
B) isotopes of hydrogen.
C) laughing gas.
D) uranium.
E) either isotopes of hydrogen or uranium or both.

Question 47

Edward Teller was

A) the head of the program to develop the world's first fission bomb.
B) the head of the program to develop the world's first nuclear reactor.
C) the discoverer of nuclear fission.
D) the inventor of radiation therapy.
E) the head of the program to develop the world's first fusion bomb.

Question 48

In a self- sustaining fusion reaction, such as occurs in the sun,

A) nuclear energy is converted to other forms of energy.
B) energy is created.
C) thermal energy is converted to nuclear energy.
D) energy is destroyed.
E) nuclear energy is created from other forms of energy.

Question 49

The four plausible routes by which terrorists might use nuclear devices include

A) acquiring radioactive material and using conventional explosive to disperse this material.
B) seizing an intact nuclear weapon.
C) Both of the above.
D) enriching natural uranium to weapons grade uranium, and building a nuclear weapon from it.
E) All of the above.

Question 50

Energetically, a fusion reaction can be self- sustaining whenever

A) the reaction proceeds from lower to higher energies on the nuclear energy curve.
B) the reaction proceeds from higher to lower energies on the nuclear energy curve.
C) the reaction proceeds from lighter nuclei to heavier nuclei on the nuclear energy curve.
D) the reaction proceeds from heavier to lighter nuclei on the nuclear energy curve.
E) the reaction obeys the principle of conservation of total energy.

Question 51

Which situation has more energy, a ² H nucleus, or a separated proton and neutron?

A) They both have the same energy, because energy is always conserved in any physical process.
B) A separated proton and neutron, because work is required to put a ² H nucleus together.
C) A ² H nucleus, because work is required to put it together beginning from a separated proton and neutron.
D) A separated proton and neutron has more energy, because work is required to pull a ² H nucleus apart.
E) A ² H nucleus, because work is required to pull a ² H nucleus apart.

Question 52

In the fusion of low- mass nuclei to make heavier nuclei

A) thermal energy is produced.
B) the final nucleus has a smaller rest- mass than the total rest- mass of the original nuclei.
C) nuclear energy is converted to other forms.
D) All of the above.

Question 53

Hydrogen must be raised to a high temperature before it will fuse. This is because

A) high temperatures are needed to overcome the strong nuclear force between hydrogen nuclei.
B) high temperatures are needed to overcome the electric repulsion between hydrogen nuclei.
C) fusion and all other forms of chemical combustion must be initiated by high temperatures.
D) this reaction consumes more thermal energy than it produces.
E) this reaction must consume a large amount of thermal energy in order to produce nuclear energy.

Question 54

Fallout from nuclear weapons or from a nuclear reactor accident is due to

A) the uranium nuclei used in the fission reaction.
B) the radioactive "fusion products" produced during the fusion reaction.
C) the neutrons produced during the fission reaction.
D) the radioactive "fission products" produced during the fission reaction.
E) chickens flying overhead.

Question 55

The two nuclei that can sustain a nuclear chain- reaction are

A) "²³⁵U and plutonium."
B) "thorium and plutonium."
C) "thorium and ²³⁵U."
D) "²³⁸U and plutonium."
E) "Actually, there is only one nucleus that can sustain a nuclear chain- reaction."

Question 56

When two ⁴ He nuclei fuse, the resulting nucleus will have

A) atomic number 4 and mass number 8.
B) mass number 4 and atomic number 8.
C) atomic number 4 and mass number 4.
D) atomic number 2 and mass number 8.
E) None of the above.

Question 57

In a nuclear reactor, how many neutrons [on the average] created during the fission of a ²³⁵U nucleus cause further fission in other uranium nuclei?

A) None
B) Less than one
C) More than one
D) One
E) Ten

Question 58

The two most plentiful elements in the universe are

A) hydrogen and helium.
B) nitrogen and helium.
C) lithium and helium.
D) carbon and oxygen.
E) hydrogen and oxygen.

Question 59

What material was used as fuel in the world's first nuclear reactor?

A) 239_Pu
B) 238_U
C) 14_C
D) 235_U
E) 2_H

Question 60

Most of the elements heavier than iron that are spread throughout the dust of the universe were created

A) during the fusion process that powers the stars, and then released in supernova explosions.
B) during the shock of a supernova explosion.
C) in the original creation of the universe.
D) in college cafeterias.
E) in hot white dwarf stars.

Question 61

J. Robert Oppenheimer was

A) the head of the program to develop the world's first nuclear reactor.
B) the inventor of radiation therapy.
C) the head of the program to develop the world's first fusion bomb.
D) the discoverer of nuclear fission.
E) the head of the program to develop the world's first fission bomb.

Question 62

Nuclear fusion creates

A) thermal energy.
B) radiant energy.
C) both thermal and radiant energy.
D) nuclear energy.
E) all types of energy.

Question 63

Which of the following is needed in order to produce a uranium fission bomb?

A) deuterium and tritium
B) plutonium
C) an isotope separation, or enrichment, facility
D) All of the above.
E) None of the above.

Question 64

In a fission bomb explosion, how many neutrons [on the average] created during the fission of a ²³⁵U nucleus cause further fission in other uranium nuclei?

A) None
B) Less than one
C) More than one
D) One
E) Ten

Question 65

Naturally occurring uranium is mostly

A) 14_U.
B) 235_U.
C) 233_U.
D) 238_U.
E) good to eat.

Question 66

When ¹H fuses with ²H to form ³He, the energy transformation could best be described as follows:

A) nuclear energy is converted into chemical energy.
B) thermal and radiant energy is converted into nuclear energy.
C) nuclear energy is converted into thermal and radiant energy.
D) chemical energy is converted into thermal energy.
E) electromagnetic energy is converted into nuclear energy.

Question 67

The bombs used against Japan were

A) a uranium bomb and a plutonium bomb.
B) two plutonium bombs.
C) two uranium bombs.
D) two fusion bombs.
E) an fission bomb and a fusion bomb.

Question 68

When two ⁴ He nuclei fuse, the energy transformation is

A) radiant E + thermal E ·nuclear E.
B) thermal E + nuclear E ·radiant E.
C) nuclear E ·radiant E + thermal E.
D) chemical E ·radiant E + thermal E.
E) thermal E ·nuclear E + radiant E.

Question 69

The four plausible routes by which terrorists might use nuclear devices include

A) acquiring radioactive material and using conventional explosive to disperse this material.
B) enriching natural uranium to weapons grade uranium, and building a nuclear weapon from it.
C) obtaining plutonium by the chemical reprocessing of used fuel rods, and building a nuclear weapon from it.
D) All of the above.
E) None of the above.

Question 70

The percentage of ²³⁵U, as a fraction of the total uranium content, in a uranium fission bomb is closest to

A) 20 percent.
B) 50 percent.
C) 90 percent.
D) 5 percent.
E) 1 percent.

Question 71

The percentage of ²³⁵U, as a fraction of the total uranium content, present in natural uranium is closest to

A) 50 percent.
B) 20 percent.
C) 1 percent.
D) 5 percent.
E) 99 percent.

Question 72

When we fission the U- 235 nucleus, the total rest- mass of all the resulting fragments of matter

A) is less than the mass of the original nucleus.
B) is more than the mass of the original nucleus
C) is turned into broccoli.
D) is the same as the mass of the original nucleus.
E) None of the above.

Question 73

In the nuclear energy curve shown in the graph above, what quantity is graphed along the vertical axis?

A) the amount of thermal energy released [per nuclear particle] by nuclear reactions of each nucleus.
B) the amount of nuclear energy [per nuclear particle] in each nucleus.
C) Both of the above.
D) the amount of work required [per nuclear particle] to fuse or fission each nucleus.
E) All of the above.

Question 74

Enrico Fermi was

A) the head of the program to develop the world's first fusion bomb.
B) the discoverer of nuclear fission.
C) the inventor of radiation therapy.
D) the head of the program to develop the world's first nuclear reactor.
E) the head of the program to develop the world's first fission bomb.

Question 75

A "supernova" is

A) a large new star.
B) a new dance step.
C) an exploding galaxy.
D) an exploding star.
E) a slight flare- up of an aged star.

Question 76

Who headed the project to construct the world's first human- made nuclear reactor?

A) Leo Szilard
B) J. Robert Oppenheimer
C) Enrico Fermi
D) Edward Teller
E) Albert Einstein

Question 77

Which particle plays the key role in sustaining a fission reaction?

A) neutron
B) quark
C) gamma photon
D) proton
E) electron