Question

Which one of the following statements is/are not correct?

• A. Oxidation number of $S$ in $(N{H}_4{)}_2{S}_2{O}_8$ is $+7$.
• B. Oxidation number of $Os$ in $Os{O}_4$ is $+8$.
• C. Oxidation number of $S$ in $H_{2}S{O}_5$ is $+8$.
• D. Oxidation number of $O$ in $K{O}_2$ is $+\frac{1}{2}$.

Answer 1

Answer: (C), (D)

Oxidation number of $S$ in $H_{2}S{O}_5$ is $+8$.
Oxidation number of $O$ in $K{O}_2$ is $+\frac{1}{2}$.

$H_{2}S{O}_5=2+x-10=0$

$\Rightarrow x=+8$

This is an impossible oxidation state of sulphur as $S:3s^{2}3p^4$ Maximum oxidation state= $+6$

Therefore, $H_{2}S{O}_3.O_2$

$\downarrow$ $\downarrow$

Oxide $(-2)$ Peroxide $(-1)$

$\Rightarrow 2+x+(-2\times 3)+(-1\times 2)=0$

$\Rightarrow 2+x-6-2=0$

$\Rightarrow x=6$.

$K{O}_2$ is a superoxide. It is made up of $K^{=}$ and $O_2^{-}$.

Therefore, single oxygen atom has $-0.5$ oxidation state. So, $K{O}_2=x-(0.5\times 2)=0$

$\Rightarrow x-1=0$

$\Rightarrow x=+1$.