In the chemical formula 5Mg3(PO4)2, what does the subscript '2' after the parentheses indicate?

• A. There are 2 magnesium atoms in each formula unit.
• B. There are 2 oxygen atoms in each phosphate ion.
• C. There are 2 phosphate ions (PO4) in each formula unit.
• D. The compound contains 2 molecules in total.

Answer: (C)

Verified step by step guidance

1. Identify the part of the chemical formula where the subscript '2' appears, which is after the parentheses in (PO4)2.
2. Understand that the parentheses group the atoms inside them as a single unit, in this case, the phosphate ion PO4.
3. Recognize that the subscript '2' outside the parentheses indicates the number of these phosphate ions present in the formula unit.
4. Note that the subscript does not apply to individual atoms inside the parentheses but to the entire group PO4 as a whole.
5. Conclude that the subscript '2' means there are 2 phosphate ions (PO4) in each formula unit of the compound.