Answer:
C. and D.
Explanation:
As the problem states, a solution containing bromothymol blue would turn from blue into yellow whenever CO₂ gas is added to it.
- When a person exhales, their breath contains CO₂. Thus blowing air into the solution through a straw would add CO₂ to the solution
- Yeast cells react with sugar and water and produce alcohol, CO₂ and energy; thus turning the solution yellow.
