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Question
The aqueous solution of one of the following salts will turn phenolphthalein indicator pink. This salt is:
Options
KCl
K2SO4
K2CO3
KNO3
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Solution
K2CO3
Explanation:
Phenolphthalein turns pink only in a basic (alkaline) solution with a pH greater than 8.2. Potassium carbonate (K2CO3) is a basic salt formed from a strong base (KOH) and a weak acid (H2CO3). When dissolved in water, it undergoes anionic hydrolysis, releasing excess hydroxide ions (OH−), thereby increasing the pH and triggering the pink colour change.
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