Question

An aqueous solution ‘A’ turns phenolphthalein solution pink. When another aqueous solution ‘B’ is added to the pink solution, the pink color disappears. Adding a few drops of solution ‘A’ again restores the pink color. The respective changes in the nature of the solution are:

• A. basic → acidic → basic
• B. acidic → basic → acidic
• C. basic → basic → acidic
• D. basic → acidic → basic

Answer 1

Answer: (D)

basic → acidic → basic

Answer 2

Phenolphthalein turns pink in a basic solution and colorless in an acidic solution. When ‘B’ neutralizes the basic nature, the color disappears, and adding ‘A’ restores the pink color.