Three is simply the coefficient which tells you the amount of molecules. In this case, there are three carbon dioxide molecules. If you want to break it down further, it also means there is three carbon atoms and six oxygen atoms.
I hope this helps.
The answer to your question is false, boiling happens below the surface of a substance.
Answer: 11.25 J
Explanation: Kinetic energy is expressed as the product of mass and the squared of velocity divided by 2.
