Methyl orange turns red in a solution and phenolphthalein remains colourless. What is the nature of the solution?
Answer and explanation
Correct answer: Acidic
Indicator colour changes reveal the solution’s acid-base nature. Methyl orange is red in an acidic medium and changes toward yellow as the medium becomes less acidic or basic. Phenolphthalein is colourless in acidic and neutral conditions, becoming pink only in a sufficiently basic solution. Both observations are therefore consistent with an acidic solution. A is correct; a basic solution would usually make phenolphthalein pink, while “metallic” is not an aqueous acid-base classification.
Frequently asked questions
What is the correct answer to this question?
Acidic
Why is this the correct answer?
Indicator colour changes reveal the solution’s acid-base nature. Methyl orange is red in an acidic medium and changes toward yellow as the medium becomes less acidic or basic. Phenolphthalein is colourless in acidic and neutral conditions, becoming pink only in a sufficiently basic solution. Both observations are therefore consistent with an acidic solution. A is correct; a basic solution would usually make phenolphthalein pink, while “metallic” is not an aqueous acid-base classification.
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.
