Question

What is the formula of the compound iron (III) phosphide?

Answer 1

For Iron (III) phosphide, since iron (III) has a charge of +3 and P has a charge of -3, they would cancel the each other's charges out and it would create $FeP$ which has one atom of Iron for every one atom of Phosphorous.

The formula of iron (III) phosphide is $FeP$