Question

A few drop of phenolphthalein are added to unknown solutiion. It acquire pink colour.Another unknown solution B is added to it drop by drop , the solution ultimately becomes colourless. predict the nature of A and B.

Answer 1

Dear Student,
Phenolpthalein is an acid-base indicator . It remains colourless in acidic solutions while turns pink in basic solution.
Solution which turns phenolpthalein solution as pink will be basic in nature while the solution B is of acidic nature .
Solution B when added will neutralize the base and will become colourless when the solution becomes acidic.
Regards!