Question

When zinc oxide is heated with carbon monoxide, the product formed is
A.Zinc carbonate
B.Carbon
C.Zinc
D.None of the these

Answer 1

We can define redox reactions as chemical reactions in which transfer of electrons takes place between two reactants. We can recognize the transfer of electrons by noticing the change in oxidation states of the species that are taking part in the reaction. Some of the examples of redox reactions are electrochemical cells (or) batteries.

Complete step by step answer:
We can say in oxidation reactions a substance loses its electrons.
Likewise, we can define reduction reactions as gain of electrons by a substance.
Oxidizing agents are those entities (molecule/ion) that accept electrons and reducing agents are entities (molecule/ion) that donate electrons. A substance that is oxidized is the reducing agent and substance that is reduced is the oxidizing agent.
The reaction of zinc oxide with carbon monoxide forms the product zinc metal and carbon dioxide.
Zinc oxide is reduced to metallic zinc and carbon monoxide is oxidized to carbon dioxide.
The chemical reaction is given as,
$ZnO + CO \to Zn + C{O_2}$
We can calculate the oxidation state of zinc in $ZnO$ as,
$x + \left( { - 2} \right) = 0$
$\Rightarrow x - 2 = 0$
$\Rightarrow x = + 2$
The oxidation state of zinc in $ZnO$ is $+ 2$.
The oxidation state of elemental zinc is zero.
Therefore, $CO$ is getting oxidized, so the reducing agent is $C{O_2}$. As $ZnO$ is getting reduced, the oxidizing agent is $ZnO$.
Therefore, we can extract metallic zinc from the reduction of zinc oxide by carbon monoxide.
Therefore, the option (C) is correct.

Note:
We can also extract metallic zinc by carbon. Carbon reduces zinc oxide to metallic zinc and gets oxidized to carbon monoxide. We can write this chemical reaction as,
$ZnO + C \to Zn + CO$
Here carbon is oxidizing, so it is the reducing agent, and zinc oxide is reducing, so it is an oxidizing agent.
Some of the common reducing agents are discussed below. Examples of some common reducing agents are,
1.Lithium aluminum hydride $\left( {LiAl{H_4}} \right)$
2.Diborane
3.Iodides such as potassium iodide
4.Thiosulfates
5.Compounds of iron (II)
6.Sodium borohydride $\left( {NaB{H_4}} \right)$