What is the name of a substance that can either donate a hydrogen ion or accept a
hydrogen ion depending on what it is reacting with (water is the most common
example)?
O acid
indicator
alkaline
O amphoteric

Water is amphoteric with both the acidic and basic characters.

Explanation:

As per the Bronsted Lowry theory of acids and bases,

Water has its own ability to either donate or accept hydrogen ions or protons.

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.