Question

A metal exists as an oxide with formula $M_{0.96}O$. Metal $M$ can exist as $M^{2+}$ and $M^{3+}$ in its oxide $M_{0.96}O$. The percentage of $M^{3+}$ in the oxide is nearly

• A. 8.3%
• B. 4.6%
• C. 5%
• D. 9.6%

Answer 1

Answer: (A)

Let, the number of $M^{2+}$ ions $=x$

Then, the number of $M^{3+}$ ions will be $0.96-x$

We know, the overall charge in the metal oxide is zero.

So, $x(2)+(0.96-x)(3)+1(-2)=0$

$\Rightarrow 2x+2.88-3x=2$

$\Rightarrow -x=-0.88$

$\Rightarrow x=0.88$

$\therefore$ Number of $M^{3+}$ ions $=0.96-0.88=0.08$

$\therefore$ Percentage of $M^{3+}$ ions $=0.08/0.96\times 100=8.33\%$