How will the addition of a catalyst affect the reaction rate of the chemical reaction?

it will cause the reaction rate to decrease.
it will not affect the reaction rate.
it will cause the reaction rate to increase.
it will cause the reaction rate to double.

It will cause the reaction rate to increase.

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.