For example, the brown crust on atoaste d marshmallow is the result of sugar changing to iffer-ent substances in a mixture called caramel. A change in matterthat produces one or more new substances is a chemicalchange, or chemical reaction. The burning of gasoline in acarâs engine is a chemical change.
How much brain power does the average person use? About only 10% Though an alluring idea, the 10 percent myth is so wrong it is almost laughable, says neurologist Barry Gordon at Johns Hopkins School of Medicine in Baltimorâ¦e.
It turns out though, that we use virtually every part of the brain, and that [most of] the brain is active almost all the time, Gordon adds. Let's put it this way: the brain represents three percent of the body's weight and uses 20 percent of the body's energy.. 3 people found this useful.