Question

Which of the following indicator gives pink colour in an alkaline solution?

• A. Methyl orange
• B. Turmeric
• C. Phenolphthalein
• D. Litmus paper

Answer 1

The correct option is C Phenolphthalein

Indicators are substances that help us to distinguish between an acid and an alkali through colour change. The following table shows different indicators and their colour in acidic and alkaline solutions.
$$\begin{array}{ccc}\text{Indicator}& \text{Colour in acidic solution}& \text{Colour in alkaline solution}\\ \text{Methyl orange}& \text{Pink}& \text{Yellow}\\ \text{Turmeric}& \text{Yellow}& \text{Brownish red}\\ \text{Phenolphthalein}& \text{Colourless}& \text{Pink}\\ \text{Litmus}& \text{Red}& \text{Blue}\end{array}$$
Thus, out of given options, only phenolphthalein gives pink colour in an alkaline solution.