Changes around us

1. Statue of liberty is green because it is coated with a thin layer of _____.
5. physical changes are ______ change.
7. An example of exothermic reaction is the reaction of _____ with water.
9. a change in state of matter.
12. Bombardier beetle makes their chemical bonds by combining hydrogen _______ and hydroquinone.
13. Breaking chemical bonds takes in energy from the surroundings.
15. The minimum amount of energy required for molecules to react with each other.

2. the catalyst used in elephant toothpaste is ______ iodide.
3. Chemical changes are permanent and ______.
4. Enzymes are biological ______.
6. making chemical bonds gives out energy to the surroundings.
8. The temperature at which an enzyme catalyses a reaction at the maximum rate.
10. Cold packs consist water and ammonium ______.
11. In physical changes the new substance have same _____ properties.
14. Chemical reactions require activation energy because some ____ in the reactant must first break before any new ____ can be formed.