Phenolphthalein becomes pink and turmeric becomes reddish-brown in a solution. Which ion is likely to be in excess?

Correct answer: Hydroxide ion

Phenolphthalein turns pink in a basic solution, and turmeric changes from yellow to reddish-brown in the presence of a base. These observations indicate that the concentration of hydroxide ions is relatively high, so OH⁻ ions are likely in excess. Hydrogen ions would indicate acidity, while chloride and nitrate ions are spectator ions and do not by themselves produce these indicator changes.