Final answer:
The set of conditions under which ΔG°rxn for the reaction A(g) → B(g) is most likely to be negative is when PA = 0.010 atm; PB = 10.0 atm, as this indicates a higher concentration of products, favoring a spontaneous reaction.
Step-by-step explanation:
Under which set of conditions is ΔG°rxn for the reaction A(g) → B(g) most likely to be negative? The conditions that favor a negative ΔG°rxn are dependent on the principle of Le Chatelier's and the Gibbs free energy equation ΔG° = ΔH° - TΔS°. For ΔG°rxn to be negative, we typically want to have a situation in which the reaction shifts towards the products. Considering the given options and knowing that the standard Gibbs free energy change is related to the equilibrium constant, a higher ratio of products to reactants would lead to a more negative ΔG standard reaction. Therefore, the condition that most likely results in a negative ΔG°rxn is when PA = 0.010 atm and PB = 10.0 atm, which indicates that products are favored over reactants according to Le Chatelier's principle.