Answer:
+2.
Step-by-step explanation:
Each phosphate ion (PO43-) has a charge of -3. Since there are two phosphate ions in the formula, the total negative charge from the phosphate ions is -6.
In order to balance the negative charge, the sum of the positive charges from the X3+ ions must be +6.
the charge of element X can be calculated as follows:
X3+ × 3 = +6
X3+ = +2
So the charge of element X in X3(PO4)2 is +2.