Sodium carbonate solution turns red indicator paper blue. What is the reason?
Answer and explanation
Correct answer: The solution is basic
The governing concept is the colour change of acid–base indicators. Red litmus or a comparable red indicator turns blue in a basic medium. Sodium carbonate is a salt of a strong base and a weak acid; its carbonate ions hydrolyse in water and generate hydroxide ions, so the solution is basic. Therefore option A is correct. It is not strongly acidic, ion-free, or pure water.
Frequently asked questions
What is the correct answer to this question?
The solution is basic
Why is this the correct answer?
The governing concept is the colour change of acid–base indicators. Red litmus or a comparable red indicator turns blue in a basic medium. Sodium carbonate is a salt of a strong base and a weak acid; its carbonate ions hydrolyse in water and generate hydroxide ions, so the solution is basic. Therefore option A is correct. It is not strongly acidic, ion-free, or pure water.
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.
