Methyl orange is red and phenolphthalein is colourless in a solution. What should be added to neutralise it?
Answer and explanation
Correct answer: Basic solution
Red methyl orange indicates an acidic medium, while colourless phenolphthalein is also consistent with an acidic solution. To neutralise an acid, a suitable base is added so that hydrogen ions react with hydroxide ions to form water: H⁺ + OH⁻ → H₂O. The quantity must be controlled to avoid making the mixture strongly basic. Therefore option A is correct; salt and sugar do not provide the required neutralisation.
Frequently asked questions
What is the correct answer to this question?
Basic solution
Why is this the correct answer?
Red methyl orange indicates an acidic medium, while colourless phenolphthalein is also consistent with an acidic solution. To neutralise an acid, a suitable base is added so that hydrogen ions react with hydroxide ions to form water: H⁺ + OH⁻ → H₂O. The quantity must be controlled to avoid making the mixture strongly basic. Therefore option A is correct; salt and sugar do not provide the required neutralisation.
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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