Question

What is the nature of the salt which dissolves in water to produce a solution which turns blue litmus to red?

Answer 1

Basic solutions turn red litmus paper blue. The salt of a weak acid and a strong base gives a basic solution. So, the given salt X is the salt of a weak acid and a strong base. When sodium carbonate is dissolved in water, it gets hydrolysed to some extent and forms sodium hydroxide and carbonic acid.