Question

When a student adds red litmus to an aqueous solution the red litmus turned blue which one of the following should be added in excess so that the change in colour is reversed

Answer 1

Here Is Your Ans ⤵

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Acid turns blue litmus paper to red

base turns red litmus paper To blue

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Hence Correct answer is Acid

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Answer 2

Answer: An acid must be added in excess to reverse the color change.

Explanation:

Litmus paper is an indicator which is used to detect the acidity or basicity of a solution. There are 2 types of litmus paper:

1. Red litmus paper: When this paper is dipped in a basic solution, it changes its color to blue and when it is dipped in acidic solution, no color change is seen.
2. Blue litmus paper: When this paper is dipped in an acidic solution, it changes its color to red and when it is dipped in basic solution, no color change is seen.

Hence, when a student add litmus to an aqueous solution and it changes its color to blue, the solution must be basic solution. So, to reverse the color change we need to add enough acid to the solution.