Final answer:
The equilibrium constant expression for the given reaction is K = [H CO] / [H+] [C O].
Step-by-step explanation:
The equilibrium constant expression for the reaction 2H+ (aq) + C2O42- (aq) < H C O (aq) is option 1) K = [H C O] / [H+] [C2O42-].
The equilibrium constant expression is derived from the balanced chemical equation of the reaction and it represents the ratio of the product concentrations to the reactant concentrations at equilibrium.
In this case, the concentration of the product HCO is divided by the concentrations of the reactants H+ and C2O42-. This ratio gives us the value of the equilibrium constant, which indicates the extent of the reaction.
For example, if the equilibrium constant value (K) is large, it means that the concentration of the product is high compared to the reactants, and the reaction proceeds to a greater extent towards the product side.