Question

Smelting involves reduction of metal oxide with:
(A) Carbon
(B) Self reduction
(C) Magnesium
(D) Aluminum

Answer 1

In Smelting, reduction of metal oxide is done by a reducing agent that is easily available and that can efficiently reduce metal oxide at a cheaper cost. Reducing agent in the smelting process forms a gas after getting oxidized.

Complete answer:
- Smelting involves heating ore of the metal in presence of a reducing agent. With the smelting process, we can obtain metals like iron, silver and copper from its ores.
- Carbon reduces metal oxide and converts itself to carbon monoxide first and then it gets further oxidized to carbon dioxide. High temperature makes the reduction of metal oxides favorable.
- Coke is a fuel also which is mainly made up of carbon only. As carbon is in zero oxidation state in coke, it can be oxidized. In earlier times, charcoal was used to reduce metal oxides, because it also contains carbon atoms in zero oxidation state.
- Carbon, Magnesium and Aluminum all can act as a reducing agent but in organic reactions generally, carbon is the preferred choice because it is easily available and cheap in cost as well. So, In the smelting process, carbon is used as a reducing agent to reduce metal oxide to its metallic form.

So, correct answer is (A) Carbon

Note: Do not choose Magnesium or Aluminum as true options because of the reason that they have higher oxidation potential than carbon. Self reduction will not make any sense in extraction of metals as itself being used as a reagent.