Question

Three test tubes contains different solutions and are labelled as A, B and C. The table below shows the observations when red and blue litmus papers were dipped in these test tubes.
Analyse the table given below and choose the correct options from the following.

$\begin{array}{cccc}& \text{Test tube A}& \text{Test tube B}& \text{Test tube C}\\ \text{Red Litmus}& \text{No change}& \text{No change}& \text{No change}\\ \text{Blue Litmus}& \text{Red}& \text{No change}& \text{Red}\end{array}$

• A. The sample in test tube B is neutral
• B. The sample in test tube C is acidic
• C. The sample in test tube A is neutral
• D. The sample in test tube A is acidic

Answer 1

Answer: (A), (B), (D)

The sample in test tube A is acidic

Litmus paper is used to identify the nature of a solution. They are available in two colours- red and blue.
The following table shows the colour of each litmus in different medium:

$\begin{array}{cccc}& \text{Acidic}& \text{Neutral}& \text{Basic}\\ \text{Red Litmus}& \text{Red}& \text{Red}& \text{Blue}\\ \text{Blue Litmus}& \text{Red}& \text{Blue}& \text{Red}\end{array}$

When a blue litmus paper was put in all these test tubes, it turned red in test tube A and C. So, we can confirm that the samples in test tube A and C were acidic.

No change in the colour of red litmus was introduced in any of the test tubes. It can be noticed that both litmus papers didn't change its colour when kept in test tube B. This means that the solution in test tube B is neutral.