Answer:
The symbols of the diphosphate ion is P₂O₇⁴⁻
Step-by-step explanation:
The compound Ca₂P₂O₇ is known as Calcium pyrophosphate. for the compound to be formed, two ions are put together. The cation Ca²⁺ and the anion P₂O₇⁴⁻. The oxidation state of calcium is always +2. The anion has to have a charge of -4 to make the formula Ca₂P₂O₇.
symbol Ca P₂O₇
oxidation state +2 -4
valency 2 4
Crossing the valency and finding the ratio of the valency after crossing
= Ca₄ (P₂O₇)₂
= Ca₂P₂O₇