A chemical reaction is carried out in a closed container. The energy absorbed by the chemical reaction is 150 kJ.
How much energy moves inward from the air or the walls of the container?
A. 75 kJ
B. 100 kJ
C. 150 kJ
D. 200 kJ

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.