2. Magnesium oxide can react with carbon dioxide present in the air to form magnesium carbonate. If a student used a very old bottle of magnesium oxide and a substantial amount of what we thought was magnesium oxide had been converted to magnesium carbonate, what physical evidence (if any) might you have observed during Part B of this experiment?

You exhale co2 which is produced during cellular respiration.  co2 combines with the water in your blood's plasma to make up one half of the body's most important buffer pair, carbonic acid.  the more physical activity you engage in, the more co2 your body is producing.  you can see this by putting some of the cabbage indicator in a glass and then blowing bubbles into it through a straw.  can you see a change in the color of the indicator?