Please solve number 5!! I’ll mark most brainliest!

Plz choose one of the compounds from the table and explain how you know the numbers of atoms in your formula. is it possible for two different compounds to be made from the exact same two elements? why or why not? with a limited number of elements (less than 120 are known), does this mean we also have a small number of compounds or do we have a large number of compounds in this world?

Can someone me with questions 15 to 17 plz.

What is the mass of 8 moles of sodium atoms