Question

CO₂ gas turns blue litmus paper:

• A. Blue
• B. Green
• C. Red
• D. Colourless

Answer 1

The correct option is C

Red

• Either the test compound is in a solution form (aqueous) or the paper used should be moist as it is a requirement for a litmus paper to show colour change.
• Carbon dioxide gas turns moist blue litmus to red.
• CO₂ being acidic turns moist blue litmus to red.

Thus, the CO₂ gas turns blue litmus paper to red due to its acidic nature.