When does phenolphthalein turn pink?



a) in the presence of a base

b) in the presence of an acid

c) when it is in a neutral solution

d) when it is reacting with a metal



Answer :

A.) Phenolphthalein is colorless in an acid, but it turns bright pink in the presence of a base.

Hope I helped you!!

Answer is: a) in the presence of a base.

Phenolphthalein is colorless in acidic solutions and pink in basic solutions.

Acid-base indicators are usually weak acids or bases and they are chemical detectors for hydrogen or hydronium cations.

Example for acid-base indicator is phenolphthalein (molecular formula C₂₀H₁₄O₄).

When solution turns phenolphthalein pink, it means it is basic (pH>7).