If a solution turns blue with litmus paper, what color does it turn with phenolphthalein?

• A. colorless
• B. green
• C. pink
• D. yellow

Answer: (C)

The main idea is how pH indicators behave. Litmus turning blue means the solution is basic (alkaline). Phenolphthalein responds to that same basic environment by turning pink (it remains colorless in acidic or neutral solutions and shifts to pink in basic ones, typically above pH ~8.2). So, a basic solution will make phenolphthalein pink. Colors like colorless, yellow, or green would not match the basic conditions in this indicator, so pink is the correct result.