From an Ellingham diagram, aluminium can reduce which of the following oxides?

1. A metal reduces only those oxides that lie **above** its own oxide line (less stable oxides). 2. $Cr_2O_3$ lies above $Al_2O_3$, so Al reduces it (thermite reaction). 3. $MgO$, $CaO$ and $Na_2O$ lie below $Al_2O_3$ (more stable), so Al cannot reduce them. _Source: Samacheer Kalvi Class 12 Chemistry Vol.1, Unit 1 'Metallurgy', §1.4.2 (applications) / NEET-2018 Q_