How could you verify that you produced carbon dioxide in your combustion reaction?

1. How could you verify that you produced carbon dioxide in your combustion reaction?
2.
What indication did you have that NH3 was produced in your decomposition reaction?
3.
If you did not neutralize the saturated citric acid before you poured it down the drain describe the potential consequences to the plumbing and the environment.Data Sheet

4. Why is it important to balance chemical equations before performing the chemical reaction?

5. In your double replacement reaction, the more reactive metal “pushed” the other one out of its place. Without using the internet where could you look to determine which metal was more reactive?