Answer:
Is pink in base solution, it provides a visual signal that a solution has changed from acid to a base, is colorless in acid solution.
Step-by-step explanation:
As all the indicator, phenolphtalein has the property that turns pink when the solution that you have reaches a value of a pH of 9 or above. From 0 to 8 in a pH scale, is colorless. This point in which an indicator changes is it called equivalence point.