Describe the volume.

We can see that the particles in the compressed vessel are not moving hence the kinetic motion is low which indicates a low temperature. In thermodynamics that can be described by Q(dot) in which leads us to describe the volume as low or not dense.

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.