PT: \(C_2H_4+Br_2\rightarrow C_2H_4Br_2\)
Ta có: \(n_{Br_2}=\dfrac{8}{160}=0,05\left(mol\right)\)
Theo PT: \(n_{C_2H_4}=n_{Br_2}=0,05\left(mol\right)\)
\(\Rightarrow\left\{{}\begin{matrix}\%m_{C_2H_4}=\dfrac{0,05.28}{3,8}.100\%\approx36,84\%\\\%m_{CH_4}\approx63,16\%\end{matrix}\right.\)