Final answer:
Carbonated beverages contain dissolved carbon dioxide gas that comes out of solution and forms bubbles when the container is opened due to the decrease in gas pressure above the liquid.
Step-by-step explanation:
When a carbonated beverage is packaged, it is done so under high CO₂ pressure, causing a large amount of carbon dioxide to dissolve in the liquid. When the container is opened, the equilibrium is disrupted, and bubbles of CO₂ rapidly exit the solution and rise to the surface. This is because the decrease in CO₂ pressure above the liquid lowers the solubility of CO₂, causing it to come out of solution as small gas bubbles.