ban co thieu dktc ko n$C_{2}H_{6}$=0.2
$n_{A}$=0.2
$C_{2}H_{6}$+3.5$O_{2}$-->2$CO_{2}$+3$H_{2}O$
0.2 0.4 0.6
=>khi đốt A
$n_{CO_{2}}$=0.6;$n_{H_{2}O}$=0.8
=>A:$C_{3}H_{8}$
nếu trắc nghiệm $n_{_{H_{2}O}}-n_{_{CO_{2}}}=n_{A}+n_{C_{2}H_{6}}$=>no $\overline{C} $ =2.5=>$C_{3}H_{8}$