Sơ đồ: \(ankan\underrightarrow{cracking}ankan+4.anken\)
=> Y chứa \(\dfrac{n_{ankan}}{n_{anken}}=\dfrac{1}{4}\)
\(n_Y=\dfrac{5,6}{22,4}=0,25\left(mol\right)\)
=> \(\left\{{}\begin{matrix}n_{ankan\left(Y\right)}=0,05\left(mol\right)\\n_{anken\left(Y\right)}=0,2\left(mol\right)\end{matrix}\right.\)
\(n_{Br_2}=n_{anken\left(Y\right)}=0,2\left(mol\right)\)
=> a = 0,2