Question

how does a phenol red - containing solution look if co₂ level is high?
multiple choice
yellow
pink
green
red

Explanation:

Phenol red is a pH indicator. When CO₂ level is high, it reacts with water to form carbonic acid (H₂CO₃), which lowers the pH of the solution. Phenol red turns yellow in acidic conditions (low pH).

Answer:

yellow