Giả sư: nCH4 =x(mol)
nC2H4 =y(mol)
-> 22,4x+22,4y=3,36(l)(*)
pt: CH4 + 2O2-to-> CO2 + 2H2O(1)
C2H4 + 3O2 -to-> 2CO2 + 2H2O(2)
CO2 + Ca(OH)2 -> CaCO3 +H2O
nCaCO3 =20:100=0,2(mol)
từ pt (1): nCO2=nCH4=x(mol)
pt (2): nCO2=2nC2H4=2y(mol)
-> x+2y=0,2(mol)(**)
từ (*) và (**)-> x=0,1(mol); y=0,05(mol)
-> VCH4=0,1.22,4=2,24(l)
-> %CH4=2,24:3,36.100%=66,67%
-> %C2H4= 100%-66,67%=33,33%