A solution turns blue litmus red but keeps phenolphthalein colourless. What is the nature of the solution?
Answer and explanation
Correct answer: Acidic
Indicators provide the governing evidence. An acidic solution changes blue litmus to red, while phenolphthalein remains colourless in an acidic or sufficiently neutral medium. The two observations together therefore identify the solution as acidic, so option A is correct. A basic solution would turn red litmus blue and generally make phenolphthalein pink. The test does not justify claiming that the solution must specifically be sodium chloride.
Frequently asked questions
What is the correct answer to this question?
Acidic
Why is this the correct answer?
Indicators provide the governing evidence. An acidic solution changes blue litmus to red, while phenolphthalein remains colourless in an acidic or sufficiently neutral medium. The two observations together therefore identify the solution as acidic, so option A is correct. A basic solution would turn red litmus blue and generally make phenolphthalein pink. The test does not justify claiming that the solution must specifically be sodium chloride.
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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