If a basic solution is diluted with water, in which direction will its pH move?
Answer and explanation
Correct answer: It will decrease toward 7
The governing concept is pH and dilution. A basic solution has a hydroxide-ion concentration greater than that of neutral water. Adding water increases volume without adding an equivalent amount of base, so the hydroxide-ion concentration decreases. Consequently, pOH decreases and pH moves downward toward 7, although the solution remains basic if it is not diluted infinitely. It does not become acidic immediately, so option A is correct.
Frequently asked questions
What is the correct answer to this question?
It will decrease toward 7
Why is this the correct answer?
The governing concept is pH and dilution. A basic solution has a hydroxide-ion concentration greater than that of neutral water. Adding water increases volume without adding an equivalent amount of base, so the hydroxide-ion concentration decreases. Consequently, pOH decreases and pH moves downward toward 7, although the solution remains basic if it is not diluted infinitely. It does not become acidic immediately, so option A is correct.
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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