Question

Choose the correct statement from the following options.

• A. Acetic acid will turn red litmus to blue.
• B. Sodium hydroxide will turn red litmus to blue.
• C. Potassium hydroxide will turn blue litmus to red.
• D. Citric acid will turn red litmus to blue.

Answer 1

The correct option is B Sodium hydroxide will turn red litmus to blue.

Litmus is a very popular natural indicator which is often used to distinguish between an acid and a base. Acids turn blue litmus to red and bases turn red litmus to blue. The change in colour of litmus in the presence of the given substances are mentioned in the table given below.
$$\begin{array}{ccc}\text{Substance}& \text{Nature}& \text{Change in colour of litmus}\\ \text{Citric acid}& \text{Acidic}& \text{Blue to red}\\ \text{Acetic acid}& \text{Acidic}& \text{Blue to red}\\ \text{Sodium hydroxide}& \text{Basic}& \text{Red to blue}\\ \text{Potassium hydroxide}& \text{Basic}& \text{Red to blue}\end{array}$$ Hence, sodium hydroxide will turn red litmus to blue.