Question

You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. Which of them will turn red litmus to blue?

• A. Acid
• B. Base
• C. Water
• D. All of these

Hint:

Use these simple mnemonic associations:
- Base turns Red to Blue (B for Base and Blue).
- Acid turns Blue to Red.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
We are given three substances: distilled water, an acidic solution, and a basic solution. We need to identify which of these solutions has the chemical property of turning red litmus paper to a blue color.

Step 2: Key Formula or Approach:
Litmus is a natural pH indicator used to detect acidity or basicity.

Step 3: Detailed Explanation:

• Litmus paper is a classic indicator that behaves differently based on the concentration of hydrogen ions (\(\text{H}^+\)) or hydroxide ions (\(\text{OH}^-\)) in a solution:
- Acidic solutions: Turn blue litmus paper red. They do not affect the color of red litmus paper.
- Neutral solutions (like distilled water): Do not change the color of either red or blue litmus paper, as their pH is neutral (\(\approx 7\)).
- Basic solutions: Turn red litmus paper blue, while leaving blue litmus paper unchanged. This is because basic solutions contain a higher concentration of hydroxide ions.

• Therefore, only the basic solution will turn the red litmus paper blue.


Step 4: Final Answer:
The base will turn red litmus to blue.