Who was the first person to present the Atomic Theory? (Just for fun)

If two objects at different te, peraure are in contact with each other what happens to their temperature

Temperature is defined as a. the equivalent of heat. b. a measure of the average kinetic energy of the individual atoms or molecules composing a substance. c. how hot or cold it is. d. the total kinetic energy of the atoms or molecules composing a substance. e. none of the above is correct.

What properties would have caused early researchers to name hydrogen "inflammable air”