The answer is; C
The radioisotopes in the interior of the earth are not in pure form and have many embedded impurities and are interspersed. Therefore when a neutron is released by a decaying atom, its chances of hitting another radioisotope atom (to continue the chain reaction) are lower than in a manmade nuclear reactor. This way, the radioactive chain reaction in the earth’s interior is not well sustained.
Long wave I think is the correct answer
There are eight protons in an Oxygen's nucleus.
The amount of kinetic energy that an object has depends on its mass or how heavy it is and how fast it is moving, or velocity