Đáp án đúng: C
63,27%.
$\displaystyle \begin{array}{l}\left\{ \begin{array}{l}\left\{ \begin{array}{l}\sum{HN{{O}_{3}}}:1\\n_{HN{{O}_{3}}}^{du}={{n}_{NaHC{{O}_{3}}}}=0,16\end{array} \right.\Rightarrow \text{n}_{\text{HN}{{\text{O}}_{\text{3}}}}^{\text{pu}}\text{=0,84}\\\text{Z}\left\{ \begin{array}{l}\text{NO}\\\text{C}{{\text{O}}_{\text{2}}}\end{array} \right.\text{+0,15}\left\{ \begin{array}{l}{{\text{O}}_{\text{2}}}\text{:0,03}\\{{\text{N}}_{\text{2}}}\text{:0,12}\end{array} \right.\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,n_{binh}^{sau\,phan\,ung}=0,24\end{array} \right.\\\Rightarrow {{n}_{Z}}+0,15=0,24+0,03\Rightarrow {{n}_{Z}}=0,12\end{array}$
Ta có ngay :
$\displaystyle \begin{array}{l}\text{0,12}\left\{ \begin{array}{l}\text{C}{{\text{O}}_{\text{2}}}\text{:b}\\\text{NO:0,12-b}\end{array} \right.\,\,\,\,\,\,\,\,\,\,\text{22}\left\{ \begin{array}{l}\text{Fe:a}\\\text{FeC}{{\text{O}}_{\text{3}}}\text{:b}\\\text{F}{{\text{e}}_{\text{3}}}{{\text{O}}_{\text{4}}}\text{:c}\end{array} \right.\Rightarrow \text{Fe(N}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{3}}}\text{:}\,\,\text{a+b+3c}\\\left\{ \begin{array}{l}\xrightarrow{\text{BTDT+BTNT}\text{.nito}}\text{3}\left( \text{a+b+3c} \right)\text{=0,84-(0,12-b)}\Rightarrow \text{3a+2b+9c=0,72}\\\xrightarrow{\text{BTE}}\text{3a+b+c=3(0,12-b)}\Rightarrow \text{3a+4b+c=0,36}\\\xrightarrow{\text{BTKL}}\text{56a+116b+232c=22}\end{array} \right.\\\Rightarrow \left\{ \begin{array}{l}\text{a=0,02}\\\text{b=0,06}\\\text{c=0,06}\end{array} \right.\Rightarrow {\scriptstyle{}^{\text{o}}\!\!\diagup\!\!{}_{\text{o}}\;}\text{F}{{\text{e}}_{\text{3}}}{{\text{O}}_{\text{4}}}\text{=63,27}{\scriptstyle{}^{\text{o}}\!\!\diagup\!\!{}_{\text{o}}\;}\end{array}$
