Which of the above reactions is NOT an oxidation-reduction (redox) reaction? A. First (blue)

B. Third (white)

C. Fourth (purple)

D. Fifth (pink)

E. Second (red)

- "the choice that is not an indicator of a chemical change is "state of matter changes". more common than not, chemical reactions produce energy in the form of light or heat. along with energy, they also produce a new substance called the product that could be in any state of matter (solid, gas, or liquid)."

dynamic equilibrium is the answer.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.