If we compare the density and temperature of the Earth's mantle to the core, what differences can we expect as we move downward into the Earth? Both the temperature and pressure increase.

A.
Both the density and temperature increase.

B.
Both the density and temperature decrease.

C.
The density increases, and the temperature decreases.

D.
The density decreases, and the temperature increases.

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.