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.
1 The human brain is the largest brain of all vertebrates relative to body size. 2  It weighs about 3.3 pounds (1.5 kilograms). 3  The brain makes up about 2 percent of a human's body weight.4  The cerebrum makes up 85 percent of the brain's weight. The brain makes up about 2 percent of a human's body weight. 2  The cerebrum makes up 85 percent of the brain's weight. 3  It contains about 86 billion nerve cells (neurons), the gray matter.