What is the typical pH range and corresponding color for a strong alkali using a universal indicator?

A strong alkali is characterized by a high pH, typically in the range of 11 to 14. When using a universal indicator, which shows different colors depending on the pH level of the solution, a strong alkali will appear purple. This color change indicates that the solution is significantly alkaline, with a pH level that strongly supports basic properties.

In this case, the combination of a pH of 11-13 aligns directly with the purple color observed in universal indicators. This correlation between high pH values and color reflects the concentration of hydroxide ions present in the solution, characteristic of strong bases such as sodium hydroxide or potassium hydroxide.

Understanding the properties of acids and bases in terms of pH and color helps in identifying solutions based on their chemical nature. The other choices represent ranges or colors that would not indicate a strong alkali, but rather would correspond to either neutral, weakly acidic, or strong acidic solutions instead. Thus, recognizing the signs of strong alkalinity through pH and color is crucial in chemistry.