Choose the electron configurations which are impossible for an unexcited atom. Example 1 – 1s22s22p4

Example 2 – 1s22s22p63s23p33d1

Example 3 – 1s22s22p83s1

Example 4 – 1s22s22p63s1

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.

if you're asking what comes out, it's steam.

im pretty sure its b