Question

Which of the following will not be oxidized by ozone ?

• A. $KI$
• B. $FeS{O}_4$
• C. $KMn{O}_4$
• D. $K_{2}Mn{O}_4$

Answer 1

Answer: (C)

$KMn{O}_4$ cannot be further oxidized by $O_3$. It has the highest $+7$ oxidation state of $Mn$ in it. Alkaline $KI$ is oxidised to potassium iodate and periodate.
$KI+3O_3\to \underset{\text{Pot. iodate}}{KI{O}_3}+3O_2$
$KI+4O_3\to \underset{\text{Pot. periodate}}{KI{O}_4}+4O_2$
It oxidises manganate to permanganate
$2K_{2}Mn{O}_4+H_{2}O+O_3\to 2KMn{O}_4+2KOH+O_2$
Acidified ferrous sulphate is oxidized to ferric sulphate
$2FeS{O}_4+H_{2}S{O}_4+O_3\to F{e}_2(S{O}_4{)}_3+H_{2}O+O_2$