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)

$96\%,$ $4\%$

If the amount of O-atoms $=100$

then, the amount of Ni-atoms $=98$

Let $N{i}^{2+}=x$, then $N{i}^{3+}=98-x$

Total charge on $100,O^{-2}$ ions $=200$

Total charge on $N{i}^{2+}$ and $N{i}^{3+}=2x+3(98-x)$

For neutrality, $2x+3(98-x)=200$

or, $x=94$.

$\%$ of $N{i}^{2+}=\frac{94}{98}\times 100=96\%$

and $\%$ of $N{i}^{3+}=100-96=4\%$.