4. given the chemical formulas of the following compounds, name each compound and state the rules you used to determine each name.
• rbf
• cuo
• (nh4)2c2o4
(note: c2o4– is called oxalate.)

I am taking the same test! ;)

1. RbF --> Rubidium Fluoride

Change fluorine to fluoride

2. CuO --> Copper (II) Oxide

Change oxygen to oxide. Oxide has a charge of -2. Since no subscripts are written, it means they have the same opposite charge. So, we use Copper (II).

3. (NH₄)₂C₂O₄ --> Ammonium Oxalate

NH₄ is ammonia, but we change it to ammonium for poly atomic ions. 

I hope this helps!

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)