What are the particles on the outer shell of an atom called?

What is the name of the type of cell division that occurs in the prokaryotic cell cycle

Earthquakes a. created the rock in arches utah b. can be caused by volcanic eruptions c. are caused by tsunami waves d. wear mountains down into hills

Ruby is conducting an investigation. an advantage of her design is that she can use a large range of variables, with that she can not be sure that one variable is the cause of another. what kind of investigation is ruby most likely conducting?