If methyl orange is red and phenolphthalein is colourless, what should be added to neutralise the solution?
Answer and explanation
Correct answer: Base
The governing concept is neutralisation, in which an acid reacts with a base to form salt and water. Red methyl orange shows that the solution is acidic; colourless phenolphthalein is also consistent with an acidic or neutral medium. Therefore, adding a suitable base will consume excess hydrogen ions and move the solution toward neutrality. More acid would worsen the condition, while sugar and sodium chloride do not neutralise the acid.
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What is the correct answer to this question?
Base
Why is this the correct answer?
The governing concept is neutralisation, in which an acid reacts with a base to form salt and water. Red methyl orange shows that the solution is acidic; colourless phenolphthalein is also consistent with an acidic or neutral medium. Therefore, adding a suitable base will consume excess hydrogen ions and move the solution toward neutrality. More acid would worsen the condition, while sugar and sodium chloride do not neutralise the acid.
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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