Dihydrogen acts as a powerful reducing agent on many metal oxides, but it cannot reduce all of them. — Hydrogen Chemistry Question

💡 Solution & Explanation

Dihydrogen can reduce oxides of metals that are less electropositive than iron (or roughly below hydrogen in the reactivity series), such as $CuO$, $PbO$, and $Fe_3O_4$. It is not a strong enough reducing agent to cleave the immense lattice energies of highly electropositive metal oxides like $Al_2O_3$, $MgO$, or $Na_2O$.