Question 1:
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?
Answer
If the colour of red litmus paper gets changed to blue, then it is a base and if there is
no colour change, then it is either acidic or neutral. Thus, basic solution can be easily
identified.Let us mark the three test tubes as A, B, and C. A drop of the solution
in A is put on the red litmus paper. Same is repeated with solution B and C. If either
of them changes colour to blue, then it is basic. Therefore, out of three, one is
eliminated. Out of the remaining two, any one can be acidic or neutral. Now a drop of
basic solution is mixed with a drop of each of the remaining two solutions separately
and then the nature of the drops of the mixtures is checked. If the colour of red
litmus turns blue, then the second solution is neutral and if there is no change in
colour, then the second solution is acidic.This is because acidic and basic solutions
neutralize each other. Hence, we can distinguish between the three types of solutions.
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