Đáp án đúng: D
0,525 mol.
$\begin{array}{l}\,\,\,\,\,\,\,\,\text{8Al}\,\,\,\,\,\,\,\,\,\,\xrightarrow{{}}\,\,\,\,\,\,\text{3N}{{\text{H}}_{\text{4}}}\text{N}{{\text{O}}_{\text{3}}}\\\frac{\text{3,24}}{\text{27}}\text{=0,12}\,\,\,\xrightarrow{{}}\,\,\,\,\,\,\text{0,045}\,\text{mol}\\\text{NH}_{\text{4}}^{\text{+}}\text{+O}{{\text{H}}^{\text{-}}}\xrightarrow{{}}\text{N}{{\text{H}}_{\text{3}}}\text{+}{{\text{H}}_{\text{2}}}\text{O}\\\text{A}{{\text{l}}^{\text{3+}}}\text{+4O}{{\text{H}}^{\text{-}}}\xrightarrow{{}}\text{Al(OH)}_{\text{4}}^{\text{-}}\\\Rightarrow \,{{\text{n}}_{\text{O}{{\text{H}}^{\text{-}}}}}\text{=}\,\text{4}{{\text{n}}_{\text{A}{{\text{l}}^{\text{3+}}}}}\text{+}{{\text{n}}_{\text{NH}_{\text{4}}^{\text{+}}}}\text{=0,525}\,\text{mol}\end{array}$
