Are all atoms (elements) neutral? and if not, how is the amount of electrons discovered?

No not all elements are neutral some are very active and they have the same number of protons as the number of electrons or else it would be an ion which would have more protons than electrons 

The answer is b on plato.

Answer:

a. energy is absorbed in the reaction.

explanation:

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.