Phenolphthalein turns pink and methyl orange appears yellow in a solution. What is the nature of the solution?

Correct answer: Basic

This question uses indicator colour changes. Phenolphthalein is colourless in acidic or neutral solution but turns pink in a basic solution, so its pink colour is decisive. Methyl orange is yellow in a neutral or basic medium and red in an acidic medium, so yellow supports the same conclusion. Thus the solution is basic and option A is correct; it is not acidic, neutral, or insoluble.