\[Fe\text{ }+\text{ }{{H}_{2}}S{{O}_{4}}~\to \text{ }FeS{{O}_{4}}~+\text{ }{{H}_{2}}~\uparrow (X)\]

Nhiệt phân KNO₃: \[KN{{O}_{3}}~\xrightarrow{{{t}^{o}}}\text{ }KN{{O}_{2}}~+\text{ }\frac{1}{2}\text{ }{{O}_{2}}~\uparrow \text{ }\left( Y \right)\]

\[KMn{{O}_{4~}}+\text{ }8HC{{l}_{}}~\to \text{ }KCl\text{ }+\text{ }MnC{{l}_{2}}~+~\frac{5}{2}C{{l}_{2}}~\uparrow (Z)+\text{ }4{{H}_{2}}O\]

Vậy các khí X,Y,Z lần lượt là H₂, O₂, Cl₂.