A mixture of ${\mathrm{CH}}_4, {\mathrm{C}}_2{\mathrm{H}}_4 \mathrm{and} {\mathrm{C}}_2{\mathrm{H}}_2$ gases are passed through a Wolf bottle containing ammonical cuprous chloride. The gas coming out is

${\mathrm{C}}_2{\mathrm{H}}_2$ reacts with ammonical cuprous chloride due to acidic nature of acetylene.

So the gas coming out is mixture of methane and ethylene.