The formula for density is divided by volume.

mass

ounces

weight

a) mass

Explanation:

density = mass/volume

Ounces are units of volume. Weight is not the same thing as mass. Weight has to do with gravity. Mass remains constant as a scalar quantity whereas weight is a vector quanitiy. For instance, although you'd have mass in outer space, you would have no weight. The simple answer is because there is no gravity in outer space. Thus, the formula for density is d = m/V.

a. energy is absorbed in the reaction.

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.