Dissociation of $C{H}_{3}COOH$ is supressed by adding

 Dissociation of $C{H}_{3}COOH$ is as follows –

$C{H}_{3}COOH\rightleftharpoons C{H}_{3}CO{O}^{-}+H^{+}$

As both $H^{+}$and $C{H}_{3}CO{O}^{-}$ are present in the RHS of the equilibrium.