How are mixtures different from compounds?
a. mixtures combine to produce salts; compounds do not.
b. mixtures can be separated by physical means; compounds cannot.
c. mixtures combine several different elements; compounds only combine one element.
d. mixtures involve particles that can be seen, like sand; compounds involve particles that cannot be seen, like air.

Which statement is true according to the kinetic theory? a. molecules of different gases with the same mass and temperature always have the same average density. b. molecules of different gases with the same mass and temperature always have the same average volume. c. molecules of different gases with the same mass and temperature always have the same pressure. d. molecules of different gases with the same mass and temperature always have the same molecular mass. e. molecules of different gases with the same mass and temperature always have the same average kinetic energy.