Question

Two solutions A and B have pH values of 2 and 9 respectively which one of these two will give a pink colour with phenolphthalein indicator?

Answer 1

Solution B with pH value 9 will give pink colour with phenolphthalein.
Concept Insight:  Bases give pink colour with phenolphthalein because a base will abstract two protons from phenolphthalein and the resulting phenolphthalein ion provides pink colour to the solution.