I'm not sure what type of fuel you're talking about. If you mean fossil fuel then kerosene has the highest density of all of the things you listed.
Answer
Electrons live inside the nucleus and carry a neutral charge.
Explanation:
It is endothermic because heat energy is supplied to make the water of crystallization evaporate and make the compound anhydrous.
Answer:
Law of Conservation of Energy
Explanation:
Answer: 15.3 carbon atoms