Em tham khảo nha:
\(\begin{array}{l}
a)\\
{n_{{H_2}}} = \dfrac{8}{2} = 4\,mol\\
{n_{C{H_4}}} = \dfrac{2}{{16}} = 0,125\,mol\\
2{H_2} + {O_2} \xrightarrow{t^0} 2{H_2}O\\
C{H_4} + 2{O_2} \xrightarrow{t^0} C{O_2} + 2{H_2}O\\
{n_{{O_2}}} = \dfrac{4}{2} + 0,125 \times 2 = 2,25\,mol\\
{m_{{O_2}}} = 2,25 \times 32 = 72g\\
b)\\
S + {O_2} \xrightarrow{t^0} S{O_2}\\
{n_{{O_2}}} = {n_S} = 0,125\,mol\\
{m_{{O_2}}} = 0,125 \times 32 = 4g
\end{array}\)