The colour of phenolphthalein indicator in dilute HNO isA. colourlessB. orangeC. pinkD. purple

Analysis of Phenolphthalein Indicator

1. Understanding Phenolphthalein: Phenolphthalein is a pH indicator commonly used in titrations. It is colorless in acidic solutions and turns pink in basic or alkaline conditions.

2. Analyzing the Environment: Dilute nitric acid (HNO₃) is a strong acid. The pH of a strong acid solution remains below 7 (usually around 1–3 for dilute acids), which is the acidic range.

3. Determining the Color: Since phenolphthalein is colorless in acidic conditions (pH < 7), and given that dilute HNO₃ falls into this category, we can conclude that the indicator will display a colorless state.

Final Answer

The colour of phenolphthalein indicator in dilute HNO₃ is A. colourless.