An unknown salt solution shows pH 8.5 and turns red litmus blue. What type of salt is it most likely to be?
Answer and explanation
Correct answer: Salt of weak acid and strong base
The governing concept is the relation between salt hydrolysis and the strengths of its parent acid and base. A pH of 8.5 is above 7, and red litmus turning blue confirms that the solution is basic. Salts formed from a weak acid and a strong base, such as sodium carbonate in the usual school-level classification, generally hydrolyse to produce a basic solution. Hence option B is correct; strong-acid/weak-base salts are usually acidic, while strong-acid/strong-base salts are approximately neutral.
Frequently asked questions
What is the correct answer to this question?
Salt of weak acid and strong base
Why is this the correct answer?
The governing concept is the relation between salt hydrolysis and the strengths of its parent acid and base. A pH of 8.5 is above 7, and red litmus turning blue confirms that the solution is basic. Salts formed from a weak acid and a strong base, such as sodium carbonate in the usual school-level classification, generally hydrolyse to produce a basic solution. Hence option B is correct; strong-acid/weak-base salts are usually acidic, while strong-acid/strong-base salts are approximately neutral.
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.
