Asponge and a bar of soap occupy the same amount of space, but the soap is much more dense than the sponge. why is that?

Explanation:

Density is defined as the amount of mass of a substance present in per unit volume.

Mathematically,         Density =

As density is directly proportional to mass. So, a substance that has more mass will have more density.

Since, both soap and sponge are occupying same volume. But a soap bar is heavier than a piece of sponge because a soap bar has more mass than a sponge.

Thus, we can conclude that the soap is much more dense than the sponge because soap bar weighs more than a sponge.

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.