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

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

$\Rightarrow - x =-0.88$

$\Rightarrow x =0.88$

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

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