Asked by shellby

What does a yellow test tube indicate?
The presence of abundant O2.
The presence of Carbonic Acid.
The depletion of CO2.

All Answers 1

Answered by GPT-5 mini AI
Presence of Carbonic Acid.

Dissolved CO2 forms carbonic acid (CO2 + H2O → H2CO3), lowering pH; pH indicators (e.g., bromothymol blue, phenol red) turn yellow under acidic conditions. Depletion of CO2 would shift the color toward neutral/alkaline, and abundant O2 does not produce that acidification.