Sodium hydroxide (NaOH) is a base, and phenolphthalein is an indicator. Here's what happens when you mix them:

* In an acidic solution: Phenolphthalein is colorless.

* In a neutral solution: Phenolphthalein is colorless.

* In a basic solution: Phenolphthalein turns pink or fuchsia.

Since sodium hydroxide is a strong base, when it's dissolved in water, the solution becomes highly basic. Therefore, the color of sodium hydroxide in phenolphthalein is pink or fuchsia.