Em tham khảo nha :

\(\begin{array}{l}
a)\\
C{H_4} + {O_2} \xrightarrow{t^0} C{O_2} + 2{H_2}O\\
2{C_3}{H_6} + 9{O_2} \xrightarrow{t^0} 6C{O_2} + 6{H_2}O\\
2{C_4}{H_{10}} + 13{O_2} \xrightarrow{t^0} 8C{O_2} + 10{H_2}O\\
b)\\
{n_{C{O_2}}} = \dfrac{{26,4}}{{44}} = 0,6mol\\
{n_{{H_2}O}} = \dfrac{{13,5}}{{18}} = 0,75mol\\
BT\,Oxi:\\
2{n_{{O_2}}} = 2{n_{C{O_2}}} + {n_{{H_2}O}}\\
 \Rightarrow {n_{{O_2}}} = \dfrac{{2 \times 0,6 + 0,75}}{2} = 0,975mol\\
{V_{{O_2}}} = 0,975 \times 22,4 = 21,84l\\
{m_{{O_2}}} = 0,975 \times 32 = 31,2g\\
\text{Theo định luật bảo toàn khối lượng ta có :}\\
m + {m_{{O_2}}} = {m_{C{O_2}}} + {m_{{H_2}O}}\\
 \Rightarrow m = 26,4 + 13,5 - 31,2 = 8,7g
\end{array}\)