There would be 2 which would be on the oxygen
Answer:
B. A chemical change occurred which caused the liquid's physical properties to change.
Explanation:
The reduction of the temperature of the system meant that the reaction absorbed heat energy from it. This shows that a chemical reaction was in progress. New products were formed, and this is proved by the change in the color to blue.
The reactant is what you begin with.
The product is what you end up with (so the answer is B)
