$MnO_4^{-}$ oxidises $(i)$ oxalate ion in acidic medium at $333 \ K$ and $(ii)$ $HCl$. For balanced chemical equations,the ratios $[MnO_4^{-} : C_2O_4^{2-}]$ in $(i)$ and $[MnO_4^{-} : HCl]$ in $(ii)$ respectively are

Chlorine is used to purify drinking water. Excess of chlorine is harmful. The excess of chlorine is removed by treating with sulphur dioxide. Present a balanced equation for this redox change taking place in water.

Which of the following is a redox reaction?

For the reaction:
$I^{-} + ClO_{3}^{-} + H_{2}SO_{4} \longrightarrow Cl^{-} + HSO_{4}^{-} + I_{2}$
The correct statement$(s)$ in the balanced equation is/are:
$A$. Stoichiometric coefficient of $HSO_{4}^{-}$ is $6$.
$B$. Iodide is oxidized.
$C$. Sulphur is reduced.
$D$. $H_{2}O$ is one of the products.

The number of moles of ferrous oxalate oxidized by one mole of $KMnO_4$ in acidic medium is

Which of the following is a redox reaction?