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HLHSscience
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Name two substances that are commonly used as fuel in nuclear fission reactors
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What is the name of the process whereby a nucleus is split into smaller parts
Nuclear fission
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Which particle must be absorbed by uranium-235 or plutonium-239 for fission to occur?
A neutron
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What is produced when an unstable nucleus splits into two smaller nuclei?
Energy, and 2 or 3 neutrons
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What is nuclear fusion?
The joining of two atomic nuclei to form a larger one
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What is the name of the process by which energy is released in stars?
Nuclear fusion
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What force pulls together dust and gas within nebulae?
Gravity
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What is the name given to the stable part of a star's lifecycle?
Main sequence
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What determines the lifecycle path of a star?
Its size
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Where are elements up to the mass of iron formed?
By a star in its stable period
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How are all the naturally occurring elements produced?
By fusion processes (either during a stars main sequence or during a supernova at the end of its life)
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What name is given to a star before it starts its main sequence?
Protostar
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What is left at the end of the biggest stars life?
Black hole
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What does a star the same size as the Sun become immediately after its main sequence?
Red Giant
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Put these into the correct sequence for a star like our sun:
white dwarf
black dwarf
protostar
red giant
main sequence
nebula
- Nebula => protostar => main sequence =>
- red giant => white dwarf => black dwarf
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What is a supernova?
An explosion at the end of the life of a large star
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What is the role of the moderator in a fission reactor?
It slows down the neutrons so that they are slow enough to be absorbed by nuclei (and so continue the chain reaction)
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How is a nuclear fission reactor controlled?
By the use of control rods which can be inserted to absorb neutrons and so slow down the chain reaction
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Why is nuclear fusion hard to achieve?
The positively charged nuclei will repel each each other and overcoming this requires a large amount of energy.
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How are planets formed?
Matter from a protostar may not all become part of the star. The remainder will eventually be drawn together by gravity to form planets, moons, asteroids and comets.
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The most common fuel in the sun is Hydrogen. Which two isotopes of hydrogen fuse to form Helium?
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