Question

When $S{O}_2$ is passed in a solution of potassium iodate, the oxidation state of iodine changes from :

• A. $+5$ to $0$
• B. $+5$ to $-1$
• C. $-5$ to $0$
• D. $-7$ to $-1$

Answer 1

Answer: (A)

$+5$ to $0$

The reaction between $S{O}_2$ and $KI{O}_3$ is given below:
$5S{O}_2+4H_{2}O+2KI{O}_3\to 4H_{2}S{O}_4+I_2+K_{2}S{O}_4$
+4 +5 +6 0
Thus, we can see that oxidation state of iodine changes fron $+5$ in $KI{O}_3$ to $0$ in $I_2$.