Analysis show that nickel oxide consists of nickel ion with 96% ions having d8 configuration and 4% having d7 configuration. Which amongst the following best represents the formula of the oxide?

Ni = 3d84s2 (At. no. : 28), ∴ Ni2+=3d8 and Ni3+=3d7Hence, 96% ion of Ni2+ and 4% ions of Ni3+ are present. Let number of O2- ion present in the crystal = x. Applying electroneutrality rule, Total positive charge = Total negative charge 96 x 2 (+ve charge) = 4 x 3 (+ve charge)                                  = x × 2 (-ve charge) 96 x 2 + 4 x 3 - 2x = 0 ∴x = 1.02 So formula of crystal Ni1.00O1.02 or Ni0.98O1.00