Suggest conditions number which, Mg reduces `SiO_(2)` and `Si` reduces `MgO`?

Explanation

From the Ellingham diagram, it is clear that that at temperature below 1966 K (m.p. of Si), Mg reduces `SiO_(2)` to Si, as below this temperature, the `Delta_(f)G^(@)` curve for the formation of `SiO_(2)` lies above the `Delta_(f)G^(@)` curve for the formation of `MgO`.
`2Mg+SiO_(2)overset(lt 1966K)rarr 2MgO+Si,Delta_(r)G^(@)=-ve`
However, above `1966K, Delta_(f)G^(@)` curve for the formation of `SiO_(2)` lies below the `Delta_(f)G^(@)` curve for the formation of MgO and hence above 1966 K, silicon reduces MgO to Mg.
`Si+2MgO overset(gt 1966K)rarrSiO_(2)+2Mg`