Solid's molecules have very high attraction forces, so the particles stay together and vibrate rather than any strong motion. Liquids have pretty strong attraction forces, but because they are weaker than solids, particles can move more freely, so they can slide against each other rather than vibrate. Gases have the least strong attraction forces compared to the two, so they can move everywhere, and as you know, gas is not constricted and it is everywhere, so gas is the answer.
Freezing the substance and condensing it will not increase the entropy of a substance. In fact, dissolving the substance into water is the only way to increase the entropy of a certain substance. The entropy increases because it diversify with each other.
In cellular respiration, glucose and oxygen react to form ATP. Water and carbon dioxide are released as byproducts.