If a solution of pH 2 is compared with a solution of pH 5, how much more acidic is the first solution?
Answer and explanation
Correct answer: Thousand times
The governing concept is that the pH scale is logarithmic: pH = −log[H⁺]. The difference between pH 2 and pH 5 is 3 units. Therefore the hydrogen-ion concentration ratio is 10³ = 1000. The pH 2 solution has one thousand times more H⁺ ions and is consequently one thousand times more acidic, so option C is correct. A difference of three is not a threefold acidity ratio.
Frequently asked questions
What is the correct answer to this question?
Thousand times
Why is this the correct answer?
The governing concept is that the pH scale is logarithmic: pH = −log[H⁺]. The difference between pH 2 and pH 5 is 3 units. Therefore the hydrogen-ion concentration ratio is 10³ = 1000. The pH 2 solution has one thousand times more H⁺ ions and is consequently one thousand times more acidic, so option C is correct. A difference of three is not a threefold acidity ratio.
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.
