Which statements are true of heterogeneous
mixtures? check all that apply.
they settle out.
they exhibit the tyndall effect.
their solutes and solvents appear as one.
they exhibit brownian motion.
they are evenly distributed mixtures.
they contain elements, compounds, and
solutions

your picture is not part of the scientific method.

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.

radioactive decay occurs in unstable atomic nuclei – that is, ones that don't have enough binding energy to hold

the nucleus together due to an excess of either protons or neutrons.

the answer would be a