Mhanfia, please help! Pressure and number of moles remained constant during this experiment. If you wanted to test one of these variables in a future experiment, how would you use your knowledge of gas laws to set up the investigation?

Explanation:

just here for the points

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.