Em tham khảo nha:
\(\begin{array}{l}
a)\\
{n_{{H_2}}} = \dfrac{1}{2} = 0,5\,mol\\
{V_A} = {V_{{H_2}}} \to {n_A} = {n_{{H_2}}} = 0,5\,mol\\
{M_A} = \dfrac{{14}}{{0,5}} = 28\,g/mol\\
{d_{A/{H_2}}} = \dfrac{{28}}{2} = 14\\
b)\\
{M_A} = 28g/mol \to A:{N_2}
\end{array}\)