If we has one mole of dollar bills to divide among all the people of the world, how many would each of the world's 4 billion inhabitants get?

1.5 x 10¹⁴atoms per person

Explanation:

A mole of substance is the amount that contains the avogadro's number of particles.

  1 mole =  6.02 x 10²³atoms

Total population of the world is 4 billion = 4 x 10⁹people;

 Amount of atom each person gets is:

                      =

                       =

                        = 1.5 x 10¹⁴atoms per person

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.