An aqueous solution feels soapy and turns red litmus blue. In which range is its pH most likely to be?
Answer and explanation
Correct answer: More than 7
The governing concept is the pH scale and the indicator behaviour of bases. A soapy feel suggests that the solution is alkaline, while turning red litmus blue is a direct test for a base. Basic solutions have a hydrogen-ion concentration lower than that of neutral water, so their pH is greater than 7. Option B describes an acidic solution, and C and D are fixed values that do not follow from the observations. Therefore, option A is correct.
Frequently asked questions
What is the correct answer to this question?
More than 7
Why is this the correct answer?
The governing concept is the pH scale and the indicator behaviour of bases. A soapy feel suggests that the solution is alkaline, while turning red litmus blue is a direct test for a base. Basic solutions have a hydrogen-ion concentration lower than that of neutral water, so their pH is greater than 7. Option B describes an acidic solution, and C and D are fixed values that do not follow from the observations. 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.
