$\stackrel{0}{\mathrm{Fe}}+\mathrm{CuSO}_{4} \rightarrow \stackrel{+2}{\mathrm{FeSO}_{4}}+\mathrm{Cu}$
$\stackrel{0}{\mathrm{Fe}}+5 \mathrm{CO} \rightarrow \stackrel{0}{\mathrm{Fe}}(\mathrm{CO})_{5}$
$\stackrel{0}{Fe}+\mathrm{H}_{2} \mathrm{O} \rightarrow \stackrel{+3}{\mathrm{Fe}_{2} \mathrm{O}_{3}}+\mathrm{H}_{2}$
above reactions shows the oxdiation state of iron for all given condition.
${P_4} + 10C{l_2}\xrightarrow{\Delta }PC{l_5}$
$S_2O_8^{2-} + 2e^- \longrightarrow 2SO_4^{2-}$
$Mn^{2+} + 4H_2O \longrightarrow MnO_4 + 8H^+ + 5e^-$
$Mn^{ 2+}$ ના $1$ મોલ ઓક્સિડાઇઝ કરવા માટે $S_2O_8^{2-}$ના કેટલા મોલ્સ જોઈએ?
${H_2}O\,\, + \,\,\,B{r_2}\,\,\,\, \to \,\,\,HOBr\,\,\, + \,\,\,HBr$