Question

Match the following indicators to the respective colour change in the acidic or basic medium:

• A. Red (acidic)
• B. Yellow (basic)
• C. Colourless (acidic)
• D. Green (basic)

Answer 1

An indicator is a chemical substance which helps to distinguish if a substance is an acid or a base. Table given below gives the colour change of indicators in acidic or basic medium:
$$\begin{array}{cccc}\text{Indicator}& \text{Colour of indicator}& \text{Acidic medium}& \text{Basic medium}\\ \text{Red litmus}& \text{Red}& \text{Red}& \text{Blue}\\ \text{Blue litmus}& \text{Blue}& \text{Red}& \text{Blue}\\ \text{Phenolphthalein}& \text{Colourless}& \text{Colourless}& \text{Pink}\\ \text{China rose}& \text{Rose}& \text{Dark pink}& \text{Green}\\ \text{Methyl orange}& \text{Orange}& \text{Red}& \text{Yellow}\end{array}$$