Which of the following metals cannot be extracted by the smelting process: Al, Zn, Fe and Pb. Give reason



Aluminium cannot be extracted by smelting process - due to the following reasons:
(i) Al being highly electropositive element has very strong
affinity for oxygen. So, $Al_{2}O_{3}$ is very stable compound and cannot be reduced by C.
(ii) On heating $Al_{2}O_{3}$ with C, aluminium carbide is formed.

2$Al_{2}O_{3}$ +9C —>$Al_{4}C_{3}$ +6CO