Name:______________________________Class:__________________ Date:__________________
Assessment
Subatomic Physics
Teacher Notes and Answers
22 Subatomic Physics
NUCLEAR REACTIONS
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Uranium-238 has a tendency to absorb
neutrons, so that any fission reaction that
takes place in uranium-238 loses energy.
This prevents a chain reaction from
occurring. Uranium-235 produces enough
neutrons and does not reabsorb them in the
process for a chain reaction to occur, and so
sustained energy from fission is produced.
10. For fusion of hydrogen isotopes to occur,
separate nuclei must be brought close
enough together for the strong force to take
effect and fuse the nuclei together. This
means that the electrostatic repulsion
between the nuclei must be overcome by
forces even greater than that repulsion.
Fusion reactors have as yet not been able to
sustain such forces long enough for practical
use of the energy obtained from the fusion
reactions. Fission reactors do not require
anything more than fuel that can produce
chain reactions, and substances that can
control those reactions, so these reactors
have proven much more practical to
construct and operate.
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Physics
1
Section Quizzes
Name:______________________________Class:__________________ Date:__________________
Assessment
Subatomic Physics
Section Quiz: Nuclear Reactions
Write the letter of the correct answer in the space provided.
_____ 1. Which of the following processes correctly describes a nuclear fission
reaction?
a. Two light nuclei bind together to produce a heavier nucleus and
energy.
b. Two heavy nuclei bind together to produce heavier nuclei and
energy.
c. A heavy nucleus splits to produce lighter nuclei and energy.
d. A heavy nucleus absorbs energy to produce lighter nuclei.
_____ 2. Which of the following processes correctly describes a nuclear fusion
reaction?
a. Two light nuclei bind together to produce a heavier nucleus and
energy.
b. Two heavy nuclei bind together to produce heavier nuclei and
energy.
c. A heavy nucleus splits to produce lighter nuclei and energy.
d. A heavy nucleus absorbs energy to produce lighter nuclei.
_____ 3. What value must the mass number of an isotope be greater than for
fission to occur?
a. 26
b. 58
c. 83
d. 112
_____ 4. What property must a substance have if it is to control a fission chain
reaction?
a. It must absorb the daughter isotopes produced during the reaction.
b. It must convert neutrons to protons during the reaction.
c. It must emit additional neutrons to be used by the reaction.
d. It must absorb a portion of the neutrons produced by the reaction.
_____ 5. What type of particle is captured by other nuclei in a nuclear chain
reaction, triggering additional fission events?
a. electrons
b. protons
c. neutrons
d. neutrinos
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Physics
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Section Quizzes
Name:______________________________Class:__________________ Date:__________________
Subatomic Physics continued
_____ 6. What is a nuclear reactor?
a. a system designed to increase the energy released from a chain
reaction
b. a system designed to start a fission chain reaction within heavy
elements
c. a system designed to start an uncontrolled, self-sustained chain
reaction
d. a system designed to maintain a controlled, self-sustained chain
reaction
_____ 7. What is the initial series of nuclear-fusion reactions that produces
energy in the sun called?
a. the hydrogen cycle
b. the proton-proton cycle
c. the hydrogen-helium cycle
d. the deuterium-hydrogen cycle
_____ 8. Which of the following is not an advantage of nuclear fusion reactors?
a. Deuterium, the fuel used for fusion, is easily obtained from water.
b. Fusion reactions produce few radioactive byproducts.
c. The repulsive forces between deuterium nuclei are easily overcome.
d. The fuel costs of a fusion reactor would be relatively low.
9. Explain why uranium-235 is used in fission reactions, but uranium-238 is not.
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10. Explain why fission reactions are much easier to harness than fusion reactions
for the commercial production of energy.
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Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Physics
3
Section Quizzes