Assertion (A): Magnesium can reduce $Al_2O_3$ at a temperature below $1350^{\circ}C$, while above $1

Question

Assertion (A): Magnesium can reduce $Al_2O_3$ at a temperature below $1350^{\circ}C$, while above $1350^{\circ}C$ aluminium can reduce MgO.\ Reason (R): The melting and boiling points of magnesium are lower than those of aluminium.

Professor PC Thomas Classes · Answer

Assertion is true based on the intersection of their Ellingham lines at ~1350°C. Reason is also true factually, but the correct explanation is the crossover of their respective $\Delta G$ of formation lines, not just their physical boiling points.