Question

the correct formula for iron ( ii) phosphide is

Explanation:

Step1: Identify ions and charges

Iron(II) has a charge of $Fe^{2+}$ (since the Roman numeral II indicates a +2 charge). Phosphide ion is $P^{3-}$ (phosphide is the anion of phosphorus, with a -3 charge).

Step2: Apply criss - cross method

To balance the charges, we take the magnitude of the charge of one ion as the subscript of the other. So, the charge of Fe ($2+$) becomes the subscript of P, and the charge of P ($3-$) becomes the subscript of Fe.

So the formula is $Fe_3P_2$.

Answer:

$\boldsymbol{Fe_3P_2}$