A salt solution shows pH 9 and turns red litmus blue. From which type of acid and base could it be formed?
Answer and explanation
Correct answer: Weak acid and strong base
The governing concept is salt hydrolysis and the strength of the parent acid and base. A pH of 9 and the change of red litmus to blue show that the salt solution is basic. Salts formed from a weak acid and a strong base commonly give basic solutions because the conjugate base of the weak acid hydrolyses water and produces hydroxide ions. Therefore option B is correct. A strong acid-weak base salt is generally acidic, while a strong acid-strong base salt is approximately neutral.
Frequently asked questions
What is the correct answer to this question?
Weak acid and strong base
Why is this the correct answer?
The governing concept is salt hydrolysis and the strength of the parent acid and base. A pH of 9 and the change of red litmus to blue show that the salt solution is basic. Salts formed from a weak acid and a strong base commonly give basic solutions because the conjugate base of the weak acid hydrolyses water and produces hydroxide ions. Therefore option B is correct. A strong acid-weak base salt is generally acidic, while a strong acid-strong base salt is 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.
