to determine whether something has gone through a chemical change you have to identify the following: 1)a new substance is formed 2)there is a change in the chemical properties of the substance undergoing whatever change 3)hard to reverse on the other hand physical changes 1) are easy to reverse with simple separation techniques 2) no new substance is formed 3) there is no change in chemical properties i believe the answer is gasoline being burnt since whenever you burn gas or fossil fuel CO2 is usually given off