Final answer:
The question pertains to the behavior of gases in chemistry, specifically diffusion and chemical reactions in controlled laboratory settings using flasks with stoppers or caps. It covers processes such as gas expansion into a vacuum and the preparation of an aqueous solution.
Step-by-step explanation:
The question involves understanding the behavior of gases and their reactions when subjected to different conditions inside three 5-L flasks. Specifically, the scenario provided describes a physical process where a gas spreads out to fill available space evenly, which is known as diffusion, and a chemical process involving nitric acid and copper creating brownish nitrogen dioxide gas. Moreover, the question references various laboratory equipment and protocols associated with the preparation and interaction of gases and solutions in a controlled environment.
Understanding these concepts is essential to grasp key principles in chemistry such as reaction stoichiometry, gas laws, and solution concentration procedures. These procedures often include using stoppers or caps to seal containers, prevent contamination, and ensure that gases do not escape. A second flask containing a vacuum illustrates gas expansion upon opening a stopcock, while creating an aqueous solution involves careful measurement and mixing of solute and solvent.