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Nuclear physics
Written by Dr. Hamza Farooq (Physics)
9 Class 12 Physics questions with answers and explanations.
Printable worksheet with answer key
All questions with answers
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Binding energy of a nucleus is the energy needed to:
- 1 Heat it
- 2 Rotate it
- 3 Add an electron
- 4 Separate it into nucleons
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Correct answer: Separate it into nucleons
It is the energy that holds the nucleons together.
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The mass defect is the difference between the:
- 1 Mass of two atoms
- 2 Mass of separate nucleons and the nucleus
- 3 Charge and mass
- 4 Atomic and mass number
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Correct answer: Mass of separate nucleons and the nucleus
The nucleus is lighter than the sum of its nucleons.
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A radioactive sample has a half life of 5 hours. After 15 hours the fraction left is:
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Correct answer: 1/8
Three half lives: (1/2)³ = 1/8.
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Beta decay increases the atomic number by:
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Correct answer: 1
In beta minus decay a neutron changes into a proton.
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A fission chain reaction is controlled in a reactor using:
- 1 Water only
- 2 More uranium
- 3 Air
- 4 Control rods
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Correct answer: Control rods
Control rods absorb neutrons.
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The energy released from 1 atomic mass unit converted completely is about:
- 1 9310 MeV
- 2 931 MeV
- 3 9.31 MeV
- 4 93 MeV
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Correct answer: 931 MeV
1 u corresponds to about 931 MeV.
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The strong nuclear force acts between:
- 1 Molecules
- 2 Electrons only
- 3 Atoms only
- 4 Nucleons
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Correct answer: Nucleons
It holds protons and neutrons together.
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A nuclear reactor uses a moderator to:
- 1 Slow down neutrons
- 2 Absorb all neutrons
- 3 Cool the fuel only
- 4 Speed up neutrons
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Correct answer: Slow down neutrons
Slow neutrons cause fission more easily.
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The unit of radioactivity is the:
- 1 Gray only
- 2 Joule
- 3 Tesla
- 4 Becquerel
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Correct answer: Becquerel
One becquerel is one decay per second.
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