Which of the following reduction reactions are actually employed in commercial…

CHEMISTRY · Single correct · CBSE · Chemistry · Metals and Non-metals · Metals and Non-metals

Problem

Which of the following reduction reactions are actually employed in commercial extraction of metals? (1)

\text{Fe}_2\text{O}_3 + 2\text{Al} \longrightarrow \text{Al}_2\text{O}_3 + 2\text{Fe}

(2)

\text{Cr}_2\text{O}_3 + 2\text{Al} \longrightarrow \text{Al}_2\text{O}_3 + 2\text{Cr}

(3)

2\text{Na}[\text{Au}(\text{CN})_2] + \text{Zn} \longrightarrow \text{Na}_2[\text{Zn}(\text{CN})_4] + 2\text{Au}

(4)

\text{Cu}_2\text{S} + \text{Pb} \longrightarrow \text{Cu} + \text{PbS} \downarrow