Question

The oxidation number of iodine in ${\mathrm{IO}}_3^{-}$ is________.

• A. $-1$
• B. $+2$
• C. $-2$
• D. $+5$

Answer 1

The correct option is D

$+5$

The explanation for the correct option

(D) $+5$

Oxidation number

"Oxidation number denotes the oxidation state of an element in a compound ascertained according to a set of rules formulated on the basis that electron pair in a covalent bond belongs entirely to a more electronegative element."

The oxidation number of iodine in ${\mathrm{IO}}_3^{-}$ is $x$.

The oxidation number of oxygen is $-2$.

$$\begin{gathered} x+\left(-2\times 3\right)=-1 \\ x=-1+6 \\ =+5 \end{gathered}$$

The oxidation number of iodine in ${\mathrm{IO}}_3^{-}$ is $+5$.

The explanation for the incorrect option

The oxidation number of iodine in ${\mathrm{IO}}_3^{-}$ is $+5$. So, options (A), (B), and (C) are incorrect.

Hence, option (D) is the correct answer.