Answer: Exhaled air containing Carbon dioxide bubbles react with water to form carbonic acid . The solution turn acidic and turn from green to yellow.
Step-by-step explanation:
Exhaled carbondioxide bubbles reacts with water to form carbonic acid, the solution will turn acidic. Carbonic acid is a weak acid that decrease pH. An indicator of it shows that the solution turns from green to yellow.
Co2+ H2O= H2Co3.
The solution then dissociate to give H ion and hydrogen carbonates ion.