Question

Giúp mình cau 12

Answer 1

\(n_{NO_2}=\dfrac{9,856}{22,4}=0,44\left(mol\right)\)

BTe: \(n_{Mg}=\dfrac{1}{2}n_{NO_2}=\dfrac{1}{2}.0,44=0,22\left(mol\right)\)

=> m_Mg = 0,22.24 = 5,28 (g)

=> \(\left\{{}\begin{matrix}\%m_{Mg}=\dfrac{5,28}{8,448}.100\%=62,5\%\\\%m_{Fe}=100\%-62,5\%=37,5\%\end{matrix}\right.\)

=> Chọn A