What most likely happens when a small amount of a base is added to an acetic acid-acetate buffer from outside?
the ph of the solution decreases.
the ph of the solution increases.
the ph of the solution may increase or decrease.
the ph of the solution remains the same.

The pH of the solution remains the same.
Buffer solutions are special solutions that contain ions that are in equilibrium. These ions work to keep the pH of the solution constant. When an acid or a base is added, the equilibrium is disturbed, and the solution behaves under Le Chatelier's principle, which states that whenever a system in equilibrium is disturbed, the system will act in such a way as to reverse the effect of the disturbance.

They are all decomposition reactions.