The answer is Carbon Dioxide. Oxygen is created during photosythesis. :)
I believe <u>hydrologic and Rock Cycles </u>is the right answer.
Explanation:
For any enthalpy change in a chemical reaction, (exothermic/endothermic), the activation energy must be reached so as to break the strong chemical bonds between the reactant molecules.
A system is contained by its boundary; therefore, the size of a system is limited by its boundary.