When a base is added to an acidic solution, universal indicator changes from red to green. What happened?
Answer and explanation
Correct answer: Neutralisation was nearly completed
The governing concept is the pH scale and neutralisation. Universal indicator is red in a strongly acidic range and green near pH 7. Adding a base consumes hydrogen ions from the acid, so acidity decreases and the pH moves toward neutrality. The change to green therefore indicates that neutralisation was nearly complete. The solution did not become more acidic or strongly basic, and a chemical reaction did occur.
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What is the correct answer to this question?
Neutralisation was nearly completed
Why is this the correct answer?
The governing concept is the pH scale and neutralisation. Universal indicator is red in a strongly acidic range and green near pH 7. Adding a base consumes hydrogen ions from the acid, so acidity decreases and the pH moves toward neutrality. The change to green therefore indicates that neutralisation was nearly complete. The solution did not become more acidic or strongly basic, and a chemical reaction did occur.
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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