If a sample of pure silver (ag) contains 3.35 x 10^22 atoms of iodine, how many moles of silver are in the sample?
a. 17.9 mol
b. 2.82 mol
c. 0.180 mol
d. 0.0556 mol

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.