$Y:\begin{cases}n_{H_2}=x mol \\n_{C_nH_{2n+2}}=y mol \end{cases}\Rightarrow \begin{cases}n_{CO_2}=ny \\n_{H_2O}=x+y(n+1) \end{cases}$$\Rightarrow \begin{cases}ny=\frac{18}{100} \\ 44ny+18[x+y(n+1)]=16,2 \end{cases}\Rightarrow \begin{cases}ny=0,18 mol \\x+y=0,28 mol \end{cases}$
Mặt khác $:x<\frac{4,704}{22,4}=0,21\Rightarrow y>0,07 mol\Rightarrow n<\frac{0,18}{0,07}\Rightarrow n=2$
$\Rightarrow C_2H_6$