Answer :
Answer: In the reaction [tex]HCO^{-}_{3} + H_{2}O \rightarrow H_{3}O^{+} + CO^{2-}_{3}[/tex], [tex]H_{2}O[/tex] acts as a base because it has accepted a hydrogen ion or proton.
Explanation:
According to Arrhenius, species which dissociate to give hydrogen ions when dissolved in a solvent like water are called acid.
A species which readily accepts a hydrogen ion or proton is called a base.
For example, [tex]HCO^{-}_{3} + H_{2}O \rightarrow H_{3}O^{+} + CO^{2-}_{3}[/tex]
Here, [tex]HCO^{-}_{3}[/tex] is donating hydrogen ion. So, it is an acid whereas [tex]H_{2}O[/tex] is accepting the hydrogen ion. Hence, [tex]H_{2}O[/tex] is a base.
Thus, we can conclude that in the reaction [tex]HCO^{-}_{3} + H_{2}O \rightarrow H_{3}O^{+} + CO^{2-}_{3}[/tex], [tex]H_{2}O[/tex] acts as a base because it has accepted a hydrogen ion or proton.