\(n_{hh}=\dfrac{5.6}{22.4}=0.25\left(mol\right)\)
\(m_{Br_2}=200\cdot\dfrac{20}{100}=40\left(g\right)\)
\(n_{Br_2}=\dfrac{40}{160}=0.25\left(mol\right)\)
\(C_2H_4+Br_2\rightarrow C_2H_4Br_2\)
\(0.25........0.25..........0.25\)
\(\)\(n_{C_2H_4}=n_{hh}=0.25\left(mol\right)\)
=> Sai đề