Final answer:
Increasing the concentration of product B in a reaction with negative ΔG will make ΔG more positive. Such a reaction is spontaneous, energetically favorable, and will increase the entropy of the universe.
Step-by-step explanation:
If a reaction A → B has a negative ΔG under experimental conditions, it indicates that the reaction is spontaneous and energetically favorable. The correct statement about such a reaction is that increasing the concentration of product B will increase the ΔG, making it more positive. This is due to the reaction quotient getting closer to equilibrium, which increases ΔG values until reaching zero at equilibrium.
A spontaneous reaction does not require coupling to a reaction with a positive ΔG to proceed, and if ΔG is negative, then by definition, the reaction is energetically favorable, not unfavorable. Regarding entropy, the formation of product B will typically increase the entropy of the system unless the reaction forms a more ordered phase, but overall the entropy of the universe always increases for any process that releases energy, as described by the second law of thermodynamics.