When Byron dropped off his oldest child at college, he felt happy, proud, and a little bit nervous. This kind of "good stressor" leads to a stress response known as

Which statement is the best definition of an atom? a) anything that has mass and occupies space. b) the smallest particle that has the properties of an element. c) a substance that cannot be broken down chemically into simpler substances. eliminate d) the smallest unit of a substance that exhibits all of the properties characteristic of that substance.