1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^2

This is the electron configuration for Strontium.

Explanation:

There are 38 protons/electrons in this configuration, it matches Strontium, which also has 38 electrons.

the answer to your question is c.

if you read the house of usher you should know that the house was haunted

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.