Question

Assertion: $Mg$ cannot be extracted by reduction of its oxide by aluminium.

Reason: $Mg$ is less electropositive than $Al$

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Answer 1

$MgO$ cannot be reduced by $Al$ because the curve of $MgO$ lies below $A{l}_2{O}_3$ in the ellingham diagram for an appreciable range of temperature. Hence, $Mg$ can reduce $A{l}_2{O}_3$ but not the opposite, as it is thermodynamically not feasible.