1. an element's atomic number is the a. sum of the protons and neutrons in an atom. b. number of protons in an atom's nucleus. c. mass of the atom. d. weight of the atom.

Atemperature inversion can cause a warm air mass to move over a colder air mass. this traps the colder air mass and prevents surface air from rising. this may result in which of these? a) smog b) acid rain c) freezing rain d) a thunderstorm