Universal indicator is red in a solution. After adding water, the colour becomes orange. What does this show?

Correct answer: Acidity decreased but the solution is still acidic

The governing concept is dilution of an acid and the colour scale of a universal indicator. Red indicates a strongly acidic solution. Adding water increases the volume, so the concentration of hydrogen ions per unit volume decreases and the acidity becomes weaker. However, dilution does not automatically remove all hydrogen ions or create a base. The orange colour therefore indicates that the solution is still acidic, but less acidic than before. Hence option A is correct; B, C, and D contradict the indicator change.