A student prepared solutions of (i) an acid and (ii) a base in two separate beakers. She forgot to label the solutions and litmus paper is not available in the laboratory. Since, both the solutions are colourless, how will she distinguish between the two?

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Ques: A student prepared the solutions of (i) an acid and (ii) a base in two different beakers. She forgot to label the solutions and litmus paper is not available in the laboratory. Since, both the solutions are colourless, how will she distinguish between the two of them?

Ans: Add phenolphthalein (which is a indicator) to a portion of each solution in separate test tube. If it turns pink, then, the beaker contains base whereas if it remains colourless, it's an acid. If phenolphthalein is not available, pH paper can also be used. Acid will turn pH paper red, base will turn pH paper blue.


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