Question

In which of the following compounds, the oxidation number of iodine is fractional?

• A. $I{F}_3$
• B. $I{F}_5$
• C. $I_3^{-}$
• D. $I{F}_7$

Answer 1

Answer: (C)

Oxidation number of iodine in given species is as follows
O.N. of iodine in $I{F}_3=+3$
O.N. of iodine in $I_3=-\frac{1}{3}$
O.N. of iodine in $I{F}_5=+5$
O.N. of iodine in $I{F}_7=+7$
Therefore, oxidation number of iodine is fractional in $I_3^{-}$.