Question

What do you observe when you add a few drops of phenolphthalein to a test tube containing acetic acid?

• A. Blue colour
• B. Red colour
• C. Colourless
• D. None of these

Answer 1

The correct option is C Colourless

Phenolphthalein is a chemical compound with the formula $C_{20}{H}_{14}{O}_4$ and is often written as "HIn" or "phph" in shorthand notation. Phenolphthalein is often used as an indicator in acid-base titrations. For this application, it turns colorless in acidic solutions and pink in basic solutions.

• Acetic acid will remain colourless in phenolphthalein.