Physical because it is still H2O
Answer: A chemical process must occur and then changes between the state of the reactants and the state of the products can be determined
Explanation: Enthalpy represents the sum of the energy of the system with the product of the pressure and volume of that system. As a thermodynamic property, it expresses the ability to release heat from the system. In fact, enthalpy tells us how much heat and work has changed during the chemical reaction under constant pressure. When measuring, measurements of the difference in enthalpy between the two states of the system is performed, before and after the chemical reaction, since total enthalpy can not be measured. This measurement of the enthalpy change can tell us, for example, whether the heat was released from the system during the reaction, or the system absorbed the heat.
I believe it is C; reasoning being that the hint for physical change is," the producing of a gas," chemical "that's new and diff. substance. "
The activation energy is the minimum amount of energy that particles must have in order for them to participate in a chemical reaction. During chemical reactions bonds are broken and formed. Particles must collide with sufficient energy in order for the initial bonds to be broken. The activation energy is that that initial minimum energy that the particles can have in order for the bonds to be broken. Stronger bonds would require more energy to be broken and therefore the activation energy for such would be higher.