Name the product formed when carbon dioxide reacts with water.

Hint: When carbon dioxide reacts with water, it produces a mild acid which is used for stabilization of water after chemical softening. It is also used in aerated soft drinks.

Complete step by step answer:
When carbon dioxide is dissolved in water, it reacts with it to form carbonic acid. The molecular formula of carbonic acid is \[{H_2}C{O_3}\]. It is also known as carbonated water. The chemical reaction describing the formation of carbonic acid is:
\[C{O_2} + {H_2}O \to {H_2}C{O_3}\]
In physiology, carbonic acid is described as volatile acid or respiratory acid because it is the only acid excreted as a gas by the lungs. It plays an important role in the bicarbonate buffer system to maintain acid–base homeostasis.
Carbonic acid, is a weak acid, forms two kinds of salts: the carbonates and the bicarbonates. Carbonic acid may lose protons to form bicarbonate ions (\[HC{O_3}^ - \]) and carbonate ions (\[C{O_3}^{ - 2}\]). If the carbonic acid releases one proton, we get a bicarbonate ion and when the bicarbonate ion loses another proton, we get a carbonate ion. In the process, protons are liberated which therefore decreases the pH of water.

Hence, the correct answer is carbonic acid.

Additional information:
Some important uses of carbonic acid are:
Carbonic acid plays an important role in respiratory gas exchange mechanisms.
Water is made fizzy by adding carbon dioxide under pressure.
In case of drug overdose or poisoning, carbonic acid is given orally to induce vomiting.

Note: Don’t confuse carbonic acid with carbolic acid. Carbolic acid is nothing but phenol and carbonic acid is \[{H_2}C{O_3}\].