Chemical Composition Pretest

Today in class, we took a pretest for our next unit, chemical composition. After taking the pretest for this unit, I know that I'll need to make sure I understand the concepts very well. With previous pretests I have recognized some information, even if I didn't know how to answer the questions; however, with this pretest I only recognized mol in some of the equations. And although I recognized mol in some equations, I have no idea how the mass of one mol of an element can be calculated.