Em tham khảo nha :
\(\begin{array}{l}
a)\\
{n_{C{H_4}}} = \dfrac{V}{{22,4}} = \dfrac{{16,8}}{{22,4}} = 0,75mol\\
{m_{C{H_4}}} = n \times M = 0,75 \times 16 = 12g\\
{N_{C{H_4}}} = n \times {N_A} = 0,75 \times 6 \times {10^{23}} = 4,5 \times {10^{23}}\\
b)\\
{m_A} = 2{m_{C{H_4}}} = 24g\\
{m_{S{O_2}}} + {m_{{N_2}}} = 24g\\
\Rightarrow 64{n_{S{O_2}}} + 28{n_{{N_2}}} = 24(1)\\
{n_{S{O_2}}}:{n_{{N_2}}} = 1:2 \Rightarrow 2{n_{S{O_2}}} - {n_{{N_2}}} = 0(2)\\
\text{Từ (1) và (2)} \Rightarrow {n_{S{O_2}}} = 0,2mol;{n_{{N_2}}} = 0,4mol\\
{n_A} = {n_{S{O_2}}} + {n_{{N_2}}} = 0,6mol\\
{V_A} = n \times 22,4 = 0,6 \times 22,4 = 13,44l
\end{array}\)