Answer
a. Mostly reactants.
b. Mostly reactants.
c. Mostly reactants.
Work Step by Step
1. Compare the strengths and identify the weaker and stronger acids and bases.
a. $H_3O^+ \gt H_3PO_4$ and $H_2{PO_4}^{2-} \gt H_2O$
$H_3PO_4$ is the weaker acid.
$H_2O$ is the weaker base.
$H_2P{O_4}^{2-}$ is the stronger base.
$H_3O^+$ is the stronger acid.
b. $HC{O_3}^- \gt H_2O$ and $OH^- \gt C{O_3}^{2-}$
c. $HF \gt HS^-$ and $S^{2-} \gt F^-$
2. If the weaker acid and base are on the reactants side, the reaction contains mostly reactants at equilibrium, and vice-versa.
a. $H_3PO_4$ and $H_2O$ on reactants: Mostly reactants.
b. $H_2O$ and $C{O_3}^{2-}$ on reactants: Mostly reactants.
c. $ HS^-$ and $F^-$ on reactants: Mostly reactants.