Question

Q. To solution A. phenolphthalein is added in a test tube the solution tuns pink. On addition of dilute HCl slowly, pink colour of phenolphthalein disappears. Explain the reason for this observation. On the addition of little more solution. A to the test tube pink colour reappears. What is the nature of solution A?

Answer 1

Hey friend, 

Solution A. is basic in nature and hcl is acidic.
So when a base is added to phenolphthalein it turns pink.
And when acid is added to phenolphthalein it remains colorless. 

Hope it helps. 
Thank you.