Give the principal quantum number that corresponds to the 1s orbital

answer; i believe that the correct answer is (a) potassium(k)

1.solid

2.carbon dioxide

3.helium

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.