Write two uses of ${\mathrm{ClO}}_2$.

Which aerosols deplete ozone?

What is produced when ${\mathrm{SO}}_2$ is dissolved in water?

Name one substance which can be used as a catalyst in the formation of ${\mathrm{SO}}_3$ from ${\mathrm{SO}}_2$. Also give the relevant chemical equation.

Write one chemical equation to show that ${\mathrm{SO}}_2$ acts as a reducing agent.

Which is the strongest oxidising agent among ${\mathrm{ClO}}_4^{-}, {\mathrm{BrO}}_4^{-}$ and ${\mathrm{IO}}_4^{-}$?

Note: There is a misprinting in the book, ${\mathrm{IO}}_4^{-}$ is written as ${\mathrm{IO}}_3^{-}$.

Draw the structure of ${\mathrm{BrO}}_4^{-}$ ion.