a, X: Fe
PT: \(Fe_2O_3+3H_2\underrightarrow{t^o}2Fe+3H_2O\)
\(2Fe+3Cl_2\underrightarrow{t^o}2FeCl_3\)
\(FeCl_3+3NaOH\rightarrow3NaCl+Fe\left(OH\right)_3\)
b, X: Zn
PT: \(ZnO+H_2\underrightarrow{t^o}Zn+H_2O\)
\(Zn+H_2SO_4\rightarrow ZnSO_4+H_2\)
\(ZnSO_4+2NaOH\rightarrow Na_2SO_4+Zn\left(OH\right)_2\)