Hint
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Answer
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It must not decay into another ___ ___
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Radioactive isotope
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It must have a short ___ ___ so it is not present in the body for a long period
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Half life
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Certain cancers can be destroyed using ionising radiation - ___
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Radiotherapy
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Gamma rays pass into the body from outside and ___ the tumour
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Destroy
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However, ___ ___ may also be damaged as the radiation passes through the body
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Healthy tissues
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You can also have radiation sources placed inside the body - eg. ___ ___ to treat prostate cancer
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Radioactive rods
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This is targeted very ___ to the tumour, causing less damage to healthy tissue
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Precisely
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In a nuclear fission reaction, a large, ___ nucleus splits into 2 smaller ones
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Unstable
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For example, a ___nucleus splits when it absorbs a neutron
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Uranium-235
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This produces 2 radioactive ___ nuclei that are roughly the same size
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Daughter
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It also releases 2+ neutrons and ___
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Energy
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These neutrons may be absorbed by other nuclei, which undergo fission and produce more neutrons: a ___ ___
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Chain reaction
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if this is not controlled there will be a ___ ___
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Nuclear explosion
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Nuclear ___ make use of controlled chain reactions
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Reactors
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Nuclear ___ is the joining of smaller nuclei to form larger nuclei
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Fusion
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During the stable period of a star's life, vast quantities of hydrogen nuclei are converted to ___ nuclei by this
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Helium
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The mass of the reactants is slightly ___ than that of the products.
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More
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The mass difference is released as ___ ___
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Thermal energy
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Nuclei need to get very ___ before fusion can happen
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Close
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Under normal conditions, the positive charges on nuclei ___ each other: electrostatic repulsion
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Repel
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High temperatures and pressures are required to allow the nuclei to move ___ enough to overcome the electrostatic repulsion
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Fast
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All experimental reactors so far have used ___ energy than they have produced to provide these conditions
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More
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Gas pressure depends on the ___ of particles in the gas
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Motion
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The particles strike the walls of the container at many different angles, so the pressure of the gas is the net force at ___ ___ to the wall
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Right angles
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Pressure can be increased by ___ the mass of a gas
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Increasing
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Pressure can be increased by ___ the temperature of a gas
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Increasing
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Pressure can be increased by ___ the volume of a gas
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Decreasing
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This is because that makes the gas particles hit the wall with a higher ___ so more force is exerted per unit volume
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Frequency
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This is either because the gas takes up more space within the region, or due to an increase in ___ ___
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Kinetic energy
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The change of a volume in a gas is ___ proportional to the change in pressure when the mass and temperature are constant
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Inversely
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Pressure (Pa) x Volume = ___
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Constant
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When a gas is ___ quickly its volume decreases quickly
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Compressed
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Its temperature can rise because ___ is being done in compressing the gas so kinetic energy of the particles increases
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Work
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