To test the presence of an acid with a strip of red litmus paper,you would:
a) dip the strip as it is in the sample and see the colour change.
b) moisten the paper with water and dil in the given sample.
c) first dip strip in common salt solution and then use it to test the sample.
d) first dip in alkaline solution and then use it to test the sample.
EXPLAIN WITH REASON.
Answers
As red litmus paper turns blue in alkaline solution, it will first turn blue. Then when it is dipped in the acid it will turn red again, confirming it is an acid.
Answer: The correct answer is Option d.
Explanation:
An acid is a substance which looses hydrogen ions and a base is defined as a substance which gains hydrogen ions.
Litmus paper is an indicator which determines the acidity or basicity of a solution. There are two types of litmus paper: Red litmus paper and blue litmus paper.
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. Now, turned blue litmus paper is dipped in acidic solution, it will change the color to red.
Hence, the correct answer is Option d.