Which of the following is the correct chemical formula for magnesium phosphate?

• A. MgPO4
• B. Mg(PO4)2
• C. Mg3(PO4)2
• D. Mg2(PO4)3

Answer: (C)

Verified step by step guidance

1. Identify the ions involved: magnesium typically forms a Mg^{2+} ion, and phosphate is the polyatomic ion PO_4^{3-}.
2. Determine the charges on each ion: Mg^{2+} has a charge of +2, and PO_4^{3-} has a charge of -3.
3. Balance the total positive and negative charges to form a neutral compound. Find the smallest whole number ratio of Mg^{2+} and PO_4^{3-} ions so that the total positive charge equals the total negative charge.
4. Calculate the ratio by finding the least common multiple (LCM) of the charges 2 and 3, which is 6. This means you need 3 Mg^{2+} ions (3 × +2 = +6) and 2 PO_4^{3-} ions (2 × -3 = -6) to balance the charges.
5. Write the chemical formula using the ratio found: Mg_3(PO_4)_2, indicating 3 magnesium ions and 2 phosphate ions combined to form a neutral compound.