Phenol Red changes color from yellow to which color?

• A. Red
• B. Blue
• C. Yellow
• D. Pink

Answer: (A)

Phenol red changes color based on the acidity or basicity of a solution. In acidic conditions it appears yellow, and when the solution becomes basic (pH around 8.2 or higher) it turns red. So the color it shifts to is red. The other colors don’t match phenol red’s color change range—blue isn’t part of its transition, yellow is the starting color, and pink isn’t typical for this indicator.