What is the chemical formula for zinc phosphate?

First, we have to find the chemical formula for zinc ion and phosphate ion.

Zinc ion is a cation, and its formula is Zn^2+,
This is because zinc atom requires 2 outer shell electrons to be removed in order to become stable.

On the other hand, phosphate ion is a anion, and its formula is PO4^3-.

In order to find the chemical formula of this ionic bond, we need to make sure their charges are balanced.

To do this, take 2+ and 3-, their least common multiple is 6, so in order to turn both charges into 6+ and 6-, we need to determine how many of that ion is needed.

So to make 2+ to 6+, we need 3 zinc ions ( +2 x 3 = 6).
And to make 3- to 6-, we need 2 phosphate ions (-3 x 2 = - 6).

Now we can just combine the chemical formulas with the number of that ion needed (you can ignore the charge)
Therefore, your answer should be Zn3(PO4)2.