You have the mythical metal element ‘X’ that can exhibit variable valences 1, 2 and 5. Which of the  following is/ are not the correct chemical formula/formulae for the compounds formed by the combination of the “X” ions with different radicals?
(A) ${\mathrm{XPO}}_4$       (B) ${\mathrm{X}}_2{\mathrm{SO}}_4$      (C) ${\mathrm{X}}_5{\mathrm{ClO}}_4$       (D) ${\mathrm{X}}_3{\mathrm{NO}}_3$