It is true that under certain condition, Mg can reduce `Al_2O_3` and Al can reduce `MgO`? What are those conditions?

Answer

Yes, below 1350°C Mg can reduce `Al_(2)O_(3)` and above 1350°C, Al can reduce MgO.This can

Explanation

~Below 1996 k `Delta_(f)G^(@)` curve for the formation of`SiO_(2)` lies above for the formataion ofMg O therefore at temparature below 1966 k Mg can reduce `SiO_(2)` to metallic
`SIO_(2) +2Mg overset(1966 K) to 2Mg O +(Si:`
`Delta _(r)G^(@)` = nagative
above 1966 k `Delta _9f)G^(@)` curve for the formation of SiO_(2) lies below the correspoding cures for the formation can reduce Mg O to Mg
`Si + Mg O overset(gt1966K) to SiO_(2) +Mg `