Question

What are the conditions of formation of carbonic acid?

Answer 1

Carbon dioxide and water form carbonic acid. This is certainly one way, perhaps the most common way, carbonic acid is formed. Now, keep in mind that the production of carbonic acid in nature is often spontaneous and in small amounts. Carbonic acid isn't randomly floating around in our air. However, through the combination of water and carbon dioxide in the atmosphere, carbonic acid can be formed. This actually explains why we may find small amounts of this acid in rainwater.