Can anyone help explain what coefficients I need to add to these 4 questions, and how to do them on my own?

What is the mass of 8 moles of sodium atoms

Consider the four elements above. which one of these elements will combine with oxygen in a 1: 1 ratio?

The chemical equation below shows the reaction of sodium (na) and chlorine (cl) to form sodium chloride (nacl). 2na + cl2 → 2nacl in this equation, which of the following is a reactant? i. sodium ii. chlorine iii. sodium chloride