Question

Analysis shows that nickel oxide has the formula $N i_{0.98} O$. The percentage of $Ni$ present as $N i^{2+}$ and $N i^{3+}$ respectively will be

• A. 99%, 1%
• B. 98%, 2%
• C. 97%, 3%
• D. 96%, 4%

Answer 1

Answer: (D)

If the amount of $O$-atoms $=100$
then, the amount of $Ni$-atoms $=98$
Let $Ni ^{2+}= x$, then $Ni ^{3+}=98- x$
Total charge on $100, O ^{-2}$ ions $=200$
Total charge on $Ni ^{2+}$ and $Ni ^{3+}=2 x +3(98- x )$
For neutrality, $2 x +3(98- x )=200$ or, $x =94$.
$\%$ of $N _{1}^{2+}=\frac{94}{98} \times 100=96 \%$
and $\%$ of $Ni ^{3+}=100-96=4 \%$.