Explanation:
According to the Bronsted-Lowry conjugate acid-base theory:
A) Conjugate base of HCl is [tex]Cl^-[/tex].
[tex]HCl+H_2O\rightarrow Cl^-+H_3O^+[/tex]
B) Conjugate base of [tex]H_3PO_4[/tex] is [tex]H_2PO_3^{-}[/tex].
[tex]H_3PO_4+H_2O\rightarrow H_2PO_3^-+H_3O^+[/tex]
C) Conjugate base of HCN is [tex]CN^-[/tex].
[tex]HCN+H_2O\rightarrow CN^-+H_3O^+[/tex]
D) Conjugate base of HF is [tex]F^-[/tex].
[tex]HF+H_2O\rightarrow F^-+H_3O^+[/tex]