$\left(X\right)\stackrel{\mathrm{KOH}}{⟶}\left(Y\right)$ (gas turns red Iitmus blue) + $\left(\mathrm{Z}\right) \stackrel{\mathrm{Zn}+\mathrm{KOH}}{\to \left(\mathrm{Y}\right)}$(gas); $\left(X\right)\stackrel{\mathrm{\Delta }}{⟶}$ gas (supports in combustion)

Identify (X) to 

$$\begin{gathered} {\mathrm{NH}}_4{\mathrm{NO}}_{3 }\stackrel{\mathrm{KOH}}{⟶}{ \mathrm{NH}}_3+{\mathrm{KNO}}_3 \\ \left(\mathrm{X}\right) \left(\mathrm{Y}\right) \left(\mathrm{Z}\right) \\ \downarrow ∆ \downarrow \mathrm{Zn}+\mathrm{KOH} \\ {\mathrm{N}}_2\mathrm{O}+{\mathrm{H}}_2\mathrm{O} {\mathrm{NH}}_3\left(Y\right) \\ \Downarrow \\ \mathrm{Supports} \mathrm{combustion} \end{gathered}$$