Physical change normally mean that the change can revert back to its orginal state, which in this case that is not possible therfore it is a chemical change.
<u>The pressure of a given amount of gas is directly proportional to its absolute temperature, provided that the volume does not change (Amontons's law)</u><u>.</u>
<u> The volume of a given amount of gas is inversely proportional to its pressure when temperature is held constant (Boyle's law).</u>
