If blue litmus turns red in a solution and phenolphthalein remains colourless, what is the nature of the solution?
Answer and explanation
Correct answer: Acidic
Blue litmus turning red is a standard indication that hydrogen ions are present and the solution is acidic. Phenolphthalein is colourless in acidic and neutral media, but it becomes pink in a sufficiently basic solution. Thus the two observations agree with an acidic solution. Basic and strongly basic options conflict with the litmus result, and “metallic” is not a solution nature identified by these indicators.
Frequently asked questions
What is the correct answer to this question?
Acidic
Why is this the correct answer?
Blue litmus turning red is a standard indication that hydrogen ions are present and the solution is acidic. Phenolphthalein is colourless in acidic and neutral media, but it becomes pink in a sufficiently basic solution. Thus the two observations agree with an acidic solution. Basic and strongly basic options conflict with the litmus result, and “metallic” is not a solution nature identified by these indicators.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
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