After adding a few drops of phenolphthalein indicator to separate HCl and NaOH solutions, what color change occurs in each solution? Choose 2 answers: A) NaOH: colorless → pink B) HCl: pink → colorless C) NaOH: colorless → colorless D) NaOH: pink → colorless E) HCl: colorless → pink F) HCl: colorless → colorless

What you are checking with phenolphthalein

Phenolphthalein is an acid-base indicator, so its color depends on whether the solution is acidic or basic.

Indicator colors you need to remember

• In acidic solution (low pH): phenolphthalein is colorless.
• In basic solution (high pH, roughly $pH > 8.2$): phenolphthalein is pink.

Apply this to each solution

• HCl is a strong acid, so the indicator remains colorless: colorless → colorless (Choice F).
• NaOH is a strong base, so the indicator turns pink: colorless → pink (Choice A).

Quick elimination of the other options

• Any option that makes HCl turn pink is wrong because acids keep phenolphthalein colorless.
• Any option that keeps NaOH colorless (or makes it lose pink) is wrong because bases make phenolphthalein pink.