Introducing substances into the air that may be harmful to living organisms or the environment is called A) photolysis
B) eutrophication
C) air pollution
D) the chimney effect
E) entropy

Each pair of clay balls represents two planetesimals. if each planetesimal is composed of the same material and is separated he the same distance, which pair experiences the frayed gravitational attraction?

The pharynx is the structure in the body that serves as a pathway of both air and food. how does the body make sure that food does not get into the lungs? the salivary glands secrete enzymes that pull food out of the air pathway. the small intestine pushes the air out of the digestive system. the pancreas breaks down food in the air pathway. the epiglottis closes the air pathway so that food will not enter it.

Explain how paleontologists use trilobite fossils as index fossils for various geologic time periods.