An experiment applies heat to a substance and produces a gas that is a new and different substance. choose the true statement.
a. this represents a physical change only.
b. this represents a chemical change only.
c. this represents both a physical and a chemical change.
d. this represents neither a physical change nor a chemical change.

Im a bit torn here, lets look at the definitions of physical and chemical changes:
physical change changes only the phase/state of a substance, but not what the substance is
chemical change is a chemical reaction where a new substance is formed and energy is given off or absorbed.
(it just started raining and it smells really nice out my window)

clearly, this cannot be just a physical reaction. i think i would be inclined to pick B. but C. could have merit as an answer too. sorry for the ambiguity x