Near the surface of a liquid, fast-moving particles can break free and become a gas.
a. true
b. false

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.

i'm pretty sure it is letter c.) car