JEE Main · 2019 · 12 Jan 2019 · Shift 1 · Redox Reactions and Electrochemistry

Hot concentrated nitric acid is a strong oxidiser and takes iodine all the way to iodic acid, $\mathrm{HIO}{}_3$, while itself being reduced to nitrogen dioxide. In $\mathrm{HIO}{}_3$ the hydrogen is $+1$ and each of the three oxygens is $-2$, so for the molecule to be neutral the iodine must be $+5$. That is its oxidation state in the product.