Answer: C) 3
The three unique elements in this compound are
- Rb = Rubidium
- P = Phosphorus
- O = Oxygen
For each molecule, there are three elements of Rubidium, one Phosphorus, and four elements of oxygen.
Side note: The compound [tex]Rb_3PO_4[/tex] is known as Trirubidium phosphate. The "tri" indicates 3 Rubidium atoms, and the phosphate part is [tex]PO_4[/tex]
