Three things that should happen for a chemical reaction to occure :
1. Position of electrons must change
2. Chemical bonds must be formed and broken between atoms and
3. No changes should happen to the nuclei
Answer is 10 units of water molecules.
Answer:

Explanation:
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In this case, since the decomposition of potassium chlorate is:

We can see a 2:3 mole ratio between potassium chlorate and oxygen (molar mass 32.0 g/mol), thus, via stoichiometry, we compute the mass of oxygen that are produced by the decomposition of 2.50 moles of this reactant:

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Answer: The values become more negative
Explanation: I just took the quiz and got it correct :)