Answer: Most rocks contain SiO2 (silica), which is a compound of silicon and oxygen that forms 74%
The answer your looking for is c hope it helps
and #rateme
The amount of stuff inside the cell and outside the cell are equal
When exercising is when the lungs work the hardest because you're using a lot of muscles and are running around and are using force in your body so the lung works really hard to make sure the body gets enough air while working out.
