Question

A student prepared solutions of (i) an acid and (ii) a base in two separate beakers. She forgot to label the solutions and litmus paper is not available in the laboratory. Since both the solutions are colourless, how will she distinguish between the two?

• A. Use of china rose
• B. Use of turmeric
• C. Use of phenolphthalein
• D. All of the above

Answer 1

Answer: (D)

All of the above

We can use $\text{phenolphthalein}$ to check which of the beakers contains acid and which one contains a base because phenolphthalein is often used as an indicator in acid-base titrations, it turns colourless in acidic solutions and pink in basic solutions.

Apart from that, we can also use other natural indicators; like China rose or turmeric.

$\text{Turmeric}$ is used as another natural indicator. Turmeric is of yellow colour. Turmeric paper turns into red when it is dipped into a basic solution. Turmeric paper does not change its colour with acid.

$\text{China rose}$ is another natural indicator. China rose solution gives dark pink (magenta) colour with acid and green colour with base.

Hence, option D is correct.