If a solution showing red colour with universal indicator turns green after adding base, what is the conclusion?
Answer and explanation
Correct answer: The solution changed from acidic to nearly neutral.
The governing principle is neutralisation. A red universal-indicator colour represents a strongly acidic region, with a relatively high hydrogen-ion concentration. Adding a base supplies hydroxide ions, which react with hydrogen ions to form water. This decreases acidity and moves the pH toward 7. Green indicates a nearly neutral mixture, so option A is correct. The result does not show that the solution became strongly basic or that the base had no effect.
Frequently asked questions
What is the correct answer to this question?
The solution changed from acidic to nearly neutral.
Why is this the correct answer?
The governing principle is neutralisation. A red universal-indicator colour represents a strongly acidic region, with a relatively high hydrogen-ion concentration. Adding a base supplies hydroxide ions, which react with hydrogen ions to form water. This decreases acidity and moves the pH toward 7. Green indicates a nearly neutral mixture, so option A is correct. The result does not show that the solution became strongly basic or that the base had no effect.
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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