If the mass is 10g and the volume
is 2cm3 what is the density?

The density is 5 g/cm3

Explanation:

The density (δ) is the ratio between the mass and the volume of a compound:

δ=m/v= 10 g/2 cm3= 5 g/cm3

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.