How many electrons are needed in the outermost energy level of atoms for most atoms to be stable?

What is the name of this hydrocarbon?

To find the enthalpy of a reaction in the lab, you measured the of the reactants and the change during the reaction.

Suppose that some of the compound spilled out of the crucible after it was heated. would that cause the percent by mass of water in the compound determined by the experiment to be too low, too high, or unchanged? briefly explain your answer.