Phenolphthalein is colourless and methyl orange is red in a solution. What is the nature of this solution?
Answer and explanation
Correct answer: Acidic
Indicator colours reveal the approximate nature of a solution. Phenolphthalein is colourless in acidic and neutral media and turns pink in a sufficiently basic medium. Methyl orange is red in an acidic medium, yellow in a basic medium, and orange near its transition range. The simultaneous observations—colourless phenolphthalein and red methyl orange—therefore indicate an acidic solution. Option B is correct; a basic solution would make methyl orange yellow and usually phenolphthalein pink.
Frequently asked questions
What is the correct answer to this question?
Acidic
Why is this the correct answer?
Indicator colours reveal the approximate nature of a solution. Phenolphthalein is colourless in acidic and neutral media and turns pink in a sufficiently basic medium. Methyl orange is red in an acidic medium, yellow in a basic medium, and orange near its transition range. The simultaneous observations—colourless phenolphthalein and red methyl orange—therefore indicate an acidic solution. Option B is correct; a basic solution would make methyl orange yellow and usually phenolphthalein pink.
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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