Final answer:
Increasing the initial concentration of acid in a solution results in a decreased percent ionization, especially in the case of weak acids, due to the common-ion effect and the shifting of equilibrium as per Le Chatelier's principle.option a) decreased
Step-by-step explanation:
In the context of acid-base chemistry, increasing the initial concentration of acid results in decreased percent ionization.
This relationship is due to the common-ion effect, where the addition of more acid increases the concentration of the conjugate base and suppresses further ionization of the acid. Therefore, as per Le Chatelier's principle, the equilibrium position shifts to the left, which means fewer acid molecules ionize. This behavior is particularly notable in solutions of weak acids, where the ionization is not complete to begin with.