Choose from the conjugate acid–base pairs F- > HF, NH3 > NH4+, and NO3- > HNO3, to complete the following equation with the pair that gives an equilibrium constant Kc > 1. _____ + H2CO3 ⇌ _____ + HCO3-

Conjugate acid-base pairs consist of two species that differ by the presence or absence of a proton (H+). When an acid donates a proton, it forms its conjugate base, while a base that accepts a proton forms its conjugate acid. Understanding these pairs is crucial for predicting the direction of acid-base reactions and the strength of acids and bases involved.

The equilibrium constant (Kc) quantifies the ratio of the concentrations of products to reactants at equilibrium for a given reaction. A Kc value greater than 1 indicates that products are favored at equilibrium, while a value less than 1 suggests that reactants are favored. This concept is essential for determining which conjugate acid-base pair will shift the equilibrium towards products in the given reaction.

The strength of an acid or base is determined by its ability to donate or accept protons, respectively. Strong acids completely dissociate in solution, while weak acids only partially dissociate. In the context of the question, identifying the stronger base from the conjugate pairs will help predict which pair will effectively react with H2CO3 to produce HCO3- and shift the equilibrium towards products.