Question

Analysis shows that nickel oxide consists of nickel ion with 96% ions having $d^8$ configuration and 4% having $d^7$ configuration. Which amongst the following best represents the formula of the oxide?

• A. $N{i}_{1.02}{O}_{1.00}$
• B. $N{i}_{0.96}{O}_{1.00}$
• C. $N{i}_{0.98}{O}_{0.98}$
• D. $N{i}_{0.98}{O}_{1.00}$

Answer 1

Answer: (D)

$Ni=3d^{8}4s^2$ (Atomic number = 28)
So $N{i}^{2+}=3d^8$ and $N{i}^{3+}=3d^7$
Hence, 96% ion of $N{i}^{2+}$ and 4% ions of $N{i}^{3+}$ are present.
Let number of $O^{2-}$ ion present in the crystal = x
Using electroneutrality rule,
Total positive charge = Total negative charge
$96\times 2(+vecharge)+4\times 3(+vecharge)$
$=x\times 2(-vecharge)$
So $96\times 2+4\times 3-2x=0$
So x = 1.02
Hence formula of the crystal is $N{i}_{1.00}{O}_{1.02}$ or $N{i}_{0.98}{O}_{1.00}$ .