[VISUAL] Ionization Energy | (kJ/mol) First | 730 Second | 1450 Third | 7700 Fourth | 10,500 The ion — Atomic Structure Chemistry Question

[VISUAL]

Ionization Energy | (kJ/mol)
First | 730
Second | 1450
Third | 7700
Fourth | 10,500

The ionization energies of an unknown element, X, are listed in the table above. Which of the following is the most likely empirical formula of a compound formed from element X and phosphorus, P ?