To solve this problem it is necessary to apply the concepts related to the change of Energy in photons and the conservation of energy.
From the theory we could consider that the energy change is subject to

Where
Initial Energy
Energy loses
Replacing we have that


Therefore the Kinetic energy of the electron once it has broken free of the metal surface is 0.8eV
Answer:
15,000,000 degrees Celsius
Explanation:
After the temperature reaches this degree, nuclear fusion begins to start.
Explanation:
This happens because the gas inside tend to expand because its temperature gets higher.
This is why the balloon that is put in a freezer for too long tend to gets smaller, because the gas temperature that is inside the balloon decreases.
(you can try it at home)
It is related to the temperature of the gas.
Answer: The working and answer can be viewed from the screenshots below. Thanks