What is a solid, natural substance made of one or more minerals and can be identified into three major groups.
igneous, sedimentary, and metamorphic.

What is a scientific theory? a. a scientist's guess about how something works b. the results of an experiment obtained using the scientific method c. a proven fact that will never change d. an idea that is backed by data from many sources

What can be found in the ionosphere

What is a substance? a. a physical property of matter b. a chemical property of matter c. an element or compound that cannot be physically separated d. characteristics used to tell the difference between mixtures