A student adds water to an acidic solution and observes that the pH changes from 2 to 4. What is the most correct meaning of this change?
Answer and explanation
Correct answer: The solution became less acidic
For an aqueous solution, pH = −log[H⁺]. Adding water dilutes the solution, lowering the hydrogen-ion concentration and increasing its pH from 2 to 4. Because pH 4 is still below 7, the solution remains acidic, but it is less acidic than before. It has not necessarily become basic, and dilution does not remove all ions. Thus A is the most accurate statement.
Frequently asked questions
What is the correct answer to this question?
The solution became less acidic
Why is this the correct answer?
For an aqueous solution, pH = −log[H⁺]. Adding water dilutes the solution, lowering the hydrogen-ion concentration and increasing its pH from 2 to 4. Because pH 4 is still below 7, the solution remains acidic, but it is less acidic than before. It has not necessarily become basic, and dilution does not remove all ions. Thus A is the most accurate statement.
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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