An acidic solution changes from pH 3 to pH 6. Approximately how much did the acidity decrease?
Answer and explanation
Correct answer: Thousand times
The pH scale is logarithmic: pH = −log[H⁺]. A rise of one pH unit means the hydrogen-ion concentration, and therefore acidity, decreases by a factor of 10. The change from pH 3 to pH 6 is three units, so the decrease is 10 × 10 × 10 = 1000 times. Thus option A is correct; three, one hundred, and ten times do not match the three-unit logarithmic change.
Frequently asked questions
What is the correct answer to this question?
Thousand times
Why is this the correct answer?
The pH scale is logarithmic: pH = −log[H⁺]. A rise of one pH unit means the hydrogen-ion concentration, and therefore acidity, decreases by a factor of 10. The change from pH 3 to pH 6 is three units, so the decrease is 10 × 10 × 10 = 1000 times. Thus option A is correct; three, one hundred, and ten times do not match the three-unit logarithmic change.
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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