A solution turns blue litmus red but keeps phenolphthalein colourless. Which conclusion is correct?
Answer and explanation
Correct answer: The solution is acidic
Indicators provide the governing evidence about the solution’s acid-base nature. Blue litmus turns red in an acidic medium, while phenolphthalein remains colourless in acidic and neutral media and turns pink in a sufficiently basic medium. The two observations are therefore consistent with acidity. They do not prove that the solution contains no salt, and a solution is not itself metallic. Thus option A is the valid conclusion.
Frequently asked questions
What is the correct answer to this question?
The solution is acidic
Why is this the correct answer?
Indicators provide the governing evidence about the solution’s acid-base nature. Blue litmus turns red in an acidic medium, while phenolphthalein remains colourless in acidic and neutral media and turns pink in a sufficiently basic medium. The two observations are therefore consistent with acidity. They do not prove that the solution contains no salt, and a solution is not itself metallic. Thus option A is the valid conclusion.
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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