Question 1 of 34intermediate🔧 ApplyLong Answer3 marks

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. If you are given only red litmus paper, how will you identify the contents of each test tube?

Correct Answer

First, dip the red litmus paper into each of the three test tubes one by one. The test tube in which the red litmus turns blue contains the basic solution, as bases change the colour of red litmus to blue.

Now, we have identified the basic solution and obtained blue litmus paper. Use this blue litmus paper to test the remaining two test tubes. The test tube that turns the blue litmus back to red contains the acidic solution, as acids change the colour of blue litmus to red.

The test tube that shows no change in colour with both red and blue litmus paper contains distilled water, which is neutral in nature.

Exercise: In-text Question (Before Section 2.1) | Q: 1 | (Page Page 2)
For More Understanding

Explanation

This question tests the student's understanding of how litmus paper works as an indicator. The key insight is that red litmus paper can be converted to blue litmus paper by dipping it in the basic solution, which can then be used to identify the acidic solution. This clever approach allows identification of all three solutions using only red litmus paper.

Solution Steps

  1. Step 1: Dip red litmus paper in all three test tubes

  2. Step 2: Identify basic solution (red litmus turns blue)

  3. Step 3: Use the blue litmus obtained to test remaining two solutions

  4. Step 4: Identify acidic solution (blue litmus turns red)

  5. Step 5: Identify distilled water (no change with either litmus)

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