Đáp án đúng: D
75%.
$\begin{array}{l}\text{CaC}{{\text{O}}_{\text{3}}}\text{+2HN}{{\text{O}}_{\text{3}}}\xrightarrow{{}}\text{Ca(N}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{2}}}\text{+C}{{\text{O}}_{\text{2}}}\text{+}{{\text{H}}_{\text{2}}}\text{O}\\\,\,\,\,\text{x}\,\text{mol}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\xrightarrow{{}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\text{x}\\\text{3FeC}{{\text{O}}_{\text{3}}}\,\text{+}\,\text{10HN}{{\text{O}}_{\text{3}}}\,\xrightarrow{{}}\,\text{3Fe(N}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{3}}}\,\text{+}\,\text{NO}\,\text{+}\,\text{C}{{\text{O}}_{\text{2}}}\,\text{+5}{{\text{H}}_{\text{2}}}\\\,\,\,\text{y}\,\text{mol}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\xrightarrow{{}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\frac{\text{y}}{\text{3}}\,\,\to \,\,\text{y}\end{array}$
Hỗn hợp khí chứa$\text{(x + y) mol}\,\text{C}{{\text{O}}_{\text{2}}}$ và$\frac{\text{y}}{\text{3}}\,\text{mol}\,\text{NO}$
Theo đề bài$\displaystyle \frac{\text{44}\,\text{(x+y)}\,\text{+}\,\text{30}\text{.}\frac{\text{y}}{\text{3}}}{\text{x}\,\text{+}\,\text{y}\,\text{+}\,\frac{\text{y}}{\text{3}}}\text{=2}\text{.20,6}\Rightarrow \text{y}\,\text{=}\,\text{3x}\,\Rightarrow \,{\scriptstyle{}^{\text{o}}\!\!\diagup\!\!{}_{\text{o}}\;}{{\text{n}}_{\text{FeC}{{\text{O}}_{\text{3}}}}}\text{=75}{\scriptstyle{}^{\text{o}}\!\!\diagup\!\!{}_{\text{o}}\;}$
