During the production of aspirin, 2.6 grams of aspirin can be formed from 2.0 grams of salicylic acid. What is the percent yield if only 1.3 grams of aspirin is produced?

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.

i think it's c. i'm not sure but i think so.

you need to have a picture of the atom that way we can answer it