Describes what we observe

Scientists obtain a great deal of the evidence they use by observing natural and experimentally generated objects and effects. Much of the standard philosophical literature on this subject comes from 20th century logical empiricists, their followers, and critics who embraced their issues and accepted some of their assumptions even as they objected to specific views.

Explanation:

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.