What isotope has 18 protons and 22 neutrons?

Argon.

Explanation:

Argon is the element having 18 protons and 22 neutrons present in its nucleus. so its atomic number is 18 and mass number is 40 if we added both number of protons and neurons. Argon belongs to noble family due to completion of outermost shell and non reactive nature. It is the third most abundant gas about 0.934% present on the earth after nitrogen and oxygen.

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.

a