$2F{e^{3 + }} + S{n^{2 + }} \to 2F{e^{2 + }} + \,\,A$
$I.{\text{ }}2Cs{\text{ }} + {\text{ }}2{H_2}O{\text{ }} \to {\text{ 2}}CsOH{\text{ }} + {\text{ }}{H_2}$
$II.{\text{ }}2Cu{I_2} \to 2CuI + {\text{ }}{I_2}$
$III.{\text{ }}N{H_4}Br + {\text{ }}KOH \to KBr{\text{ }} + {\text{ }}N{H_3} + {\text{ }}{H_2}O$
$IV.{\text{ }}4KCN{\text{ }} + {\text{ }}Fe{\left( {CN} \right)_2} \to {K_4}\left[ {Fe{{\left( {CN} \right)}_6}} \right]$