Question

Which formula represents strontium phosphate?

Answer 1

Strontium has a charge of 2+ as an ion, and $PO_{4}$ a charge of -3. So to get an equal charge, the least common multiple is 6, so you would need 3 Strontium ions and you would need 2 phosphate ions. Keep in mind that you have to multiply the entire ion, so you would need to have $(PO_{4})_{2}$, NOT $PO_{8}$ because then you would only have 1 phosphorous, and that would not be phosphate anymore.
So the correct one is #4

Answer 2

Answer: The correct answer is Option 3.

Explanation:

Strontium is the 38th element of the periodic table having electronic configuration of $[Kr]5s^2$

This element will loose 2 electrons to form $Sr^{2+}$ ion.

Phosphate ion is the polyatomic ion having formula of $PO_4^{3-}$

By criss-cross method, the oxidation state of the ions form the subscript of the other atom which represents the number of atoms.

Hence, the chemical formula of strontium phosphate becomes $Sr_3(PO_4)_2$

Thus, the correct answer is Option 3.