Question

The ${H_2}S{O_3}$ acts as:
A.Reducing agent
B.Oxidizing agent
C.Only monobasic acid
D.None of these

Answer 1

We can say redox reactions are those chemical reactions which involve transfer of electrons taking place among two reactants. We can distinguish the transferral of electrons by seeing the change in oxidation states of the species that are happening in the reaction. Some of the examples of redox reactions are electrochemical cells (or) batteries.

Complete answer:
We can say in oxidation reactions electrons are lost by substances.
Likewise, we can define reduction reactions electrons are gained by substances.
Oxidizing agents are those species (molecule/ion) that receive electrons and reducing agents are species (molecule/ion) that give electrons. A substance that is oxidized is the reducing agent and substance that is reduced is the oxidizing agent.
A reducing agent is a chemical entity which loses electrons to other substances in a redox reaction and is oxidized to an oxidation state that is higher.
We must remember that the sulfurous acid has a formula of ${H_2}S{O_3}$. This compound is produced when sulfur dioxide $\left( {S{O_2}} \right)$is dissolved in water. As sulfurous acid is a weak acid, it is not as destructive as strong acids such as hydrochloric acid or sulfuric acid, and it is an oxoacid because it is an acid that contains oxygen atoms in its chemical formula.
Sulfurous acid plays the role of a good reducing agent as it has the tendency to take up oxygen from the air and several other substances which are rich in oxygen. It also shows good bleaching properties.
Therefore, the option (A) is correct.

Note:
In some cases, sulfurous acid acts as oxidizing agent as well as reducing agent as they have the ability to gain and lose electrons. Few of the common reducing agents are can be listed out below as,
-Lithium aluminum hydride $\left( {LiAl{H_4}} \right)$
-Diborane
-Iodides such as potassium iodide
-Thiosulfates
-Compounds of iron (II)
-Sodium borohydride $\left( {NaB{H_4}} \right)$.