If the pH of a basic solution changes from 13 to 11, approximately how did its basicity change?
Answer and explanation
Correct answer: Decreased one hundred times
The pH scale is logarithmic, and pOH = 14 − pH at 25°C. At pH 13, pOH is 1; at pH 11, pOH is 3. Thus the hydroxide-ion concentration changes from about 10⁻¹ M to 10⁻³ M, a decrease by 10², or 100 times. The solution remains basic at pH 11, but it is much less basic. Therefore option A is correct.
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What is the correct answer to this question?
Decreased one hundred times
Why is this the correct answer?
The pH scale is logarithmic, and pOH = 14 − pH at 25°C. At pH 13, pOH is 1; at pH 11, pOH is 3. Thus the hydroxide-ion concentration changes from about 10⁻¹ M to 10⁻³ M, a decrease by 10², or 100 times. The solution remains basic at pH 11, but it is much less basic. Therefore 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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