Which statement describes the structure of an atom? 1)the nucleus contains positively charged electrons. 2)the nucleus contains negatively charged protons. 3)the nucleus has a positive charge and is surrounded by negatively charged electrons 4)the nucleus has a negative charge and is surrounded by positively charged electrons 4)

the link still does not work even when adding it to the url bar

explanation:

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.