Question

How is the presence of an acid tested with a strip of red litmus paper ?
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Answer 1

Answer:

Red litmus paper when dipped in basic solution will turn into blue. Blue litmus paper when dipped in acidic solution will turn into red. Now, to test the presence of acid with a strip of red litmus paper, we need to first dip the litmus paper in basic or alkaline solution, it will turn from red to blue.

Explanation:

Answer 2

Since red litmus shows no colour change with acids it is first to be changed to blue litmus. So first dip the strip in alkaline solution and then use it to test the sample.

Hopefully this helps!!