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.
<span>If thermal energy (heat) must be added to a chemical reaction in order for the reaction to take place, the reaction is endothermic. </span>
Explanation: Skeletal muscle, attached to bones, is responsible for skeletal movements. The peripheral portion of the central nervous system (CNS) controls the skeletal muscles. Thus, these muscles are under conscious, or voluntary, control. The basic unit is the muscle fiber with many nuclei. These muscle fibers are striated (having transverse streaks) and each acts independently of neighboring muscle fibers.
This movement is known as convection or convection currents. This occurs due to the fact that warmer fluid is of lower density than colder fluid. This causes warmer fluid to rise and colder fluid to sink. This creates circulatory currents within the body of the fluid.
