a) \(Fe_3O_4+4H_2\rightarrow3Fe+4H_2O\left(1\right)\)
\(CuO+H_2\rightarrow Cu+H_2O\)
b) Gọi số mol \(Fe_3O_4,CuO\) lần lượt là x,y(mol)
Ta có: \(\left\{{}\begin{matrix}232x+80y=35,2\\168x+64y=26,4\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}x=0,1\\y=0,15\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}m_{Fe_3O_4}=0,1.232=23,2\left(g\right)\\m_{CuO}=0,15.80=12\left(g\right)\end{matrix}\right.\)