Answer: The pair that consists of a base and its conjugate acid in that order.[tex]NH_3/NH_4^+[/tex]
Explanation:
According to the Bronsted-Lowry conjugate acid-base theory, an acid is defined as a substance which looses donates protons and thus forming conjugate base and a base is defined as a substance which accepts protons and thus forming conjugate acid.
[tex]H_3PO_4\rightarrow H_PO_4{2^-}+2H^+[/tex]
[tex]H_2CO_3\rightarrow HCO_3^-+H^+[/tex]
[tex]NH_3+H^+\rightarrow NH_4^+[/tex]
[tex]HCO_3^-\rightarrow CO_3^{2-}+H^+[/tex]
[tex]NH_3[/tex] is gaining a proton, thus it is considered as a brønsted-lowry base and after gaining a proton, it forms[tex]NH_4^+[/tex] which is a conjugate acid.
