In the redox reaction, taking place in acidic medium: $\mathrm{X} \mathrm{MnO}_4^{-}(\mathrm{aq})+\mathrm{YSO}_2(\mathrm{~g}) \rightarrow \mathrm{Mn}^{+2}(\mathrm{aq})+\mathrm{HSO}_4^{-}(\mathrm{aq})$, the ratio of $X: Y$ in a stoichiometrically balanced equation will be

$x$ moles of $\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ oxidises 1 mole of ferrous oxalate, in acidic medium. Hence ' $x$ ' is:

In the reaction,

$$ \mathrm{Cr}_2 \mathrm{O}_7^{2-}+4 \mathrm{H}_2 \mathrm{O}_2+2 \mathrm{H}^{+} \rightarrow 2 \mathrm{CrO}_5+\mathrm{H}_2 \mathrm{O} $$

The change in oxidation state of Cr is:

Identify the correct coefficients (a), (b), (c) and (d) in the following equations

i) $\quad \mathrm{xMnO}_4^{--}+$(a) $\mathrm{SO}_3{ }^{2-}+$ (b) $\mathrm{H}^{+} \cdots \longrightarrow \mathrm{xMn}^{2+}+$ (a) $\mathrm{SO}_4{ }^{2-}+$ (c) $\mathrm{H}_2 \mathrm{O}$

ii) (c) $\mathrm{S}_2 \mathrm{O}_3{ }^{2-}+$ (d) $\mathrm{MnO}_4^{-}+\mathrm{H}_2 \mathrm{O} \cdots \rightarrow$ (d) $\mathrm{MnO}_2+$ (b) $\mathrm{SO}_4{ }^{2-}+\mathrm{xOH}^{-}$