Em tham khảo nha :
\(\begin{array}{l}
CTHH:F{e_x}{O_y}\\
\% Fe = \dfrac{{x{M_{Fe}}}}{{x{M_{Fe}} + y{M_O}}} \times 100\% = 70\% \\
\Rightarrow \dfrac{{56x}}{{56x + 16y}} = 0,7\\
\Rightarrow \dfrac{x}{y} = \dfrac{{11,2}}{{16,8}} = \dfrac{2}{3}\\
\Rightarrow CTHH:F{e_2}{O_3}\\
PTK:2 \times 56 + 3 \times 16 = 160g/mol
\end{array}\)