Steel differs from pig iron and wrought iron in that it contains

Explain the Hall-Heroult process.

In the extraction of which of the following,a complex ion is formed?

Statement $I :$ Leaching of gold with cyanide ion in absence of air $/$ $O_2$ leads to cyano complex of $Au(III)$.
Statement $II :$ Zinc is oxidized during the displacement reaction carried out for gold extraction.
In the light of the above statements,choose the correct answer from the options given below.

How are the most electropositive metals extracted from their ores?

Which of the following oxides is not reduced by carbon reduction for its commercial extraction?