Question

In self-reduction, the reducing species is
(A) S
(B) ${{O}^{2-}}$
(C) ${{S}^{2-}}$
(D) $S{{O}_{2}}$

Answer 1

Hint: The cations of the less electropositive metals like Pb, Hg, Sb and Cu may be reduced without the use of any additional reducing agent is called self reduction. For example, in the extraction of mercury, the sulphide ore (cinnabar) is heated in a current of air when the following reactions take place.

Complete step by step answer:
Oxidation may be defined as loss of electrons from a substance, the other definition of oxidation reactions states that addition of oxygen or the more electronegative element or removal of hydrogen or the more electropositive element from a substance is called an oxidation reaction.
Like oxidation reactions, reduction reactions are defined as the gain of electrons. Any substance that gains electrons during a chemical reaction gets reduced.In other forms, the reduction reaction is stated as the addition of hydrogen or more electropositive element or removal of a more electronegative element or oxygen from a substance.
For the given question,
\[C{{u}_{2}}S+2C{{u}_{2}}O\to 6C{{u}_{(Blister copper)}}+S{{O}_{2}}\uparrow \]
${{S}^{2-}}\to {{S}^{4+}}$is oxidation, that is, ${{S}^{2-}}$ is the reducing agent.

Copper(I) oxide react with copper(I) sulfide to produce copper and sulfur dioxide. This reaction takes place at a temperature of $1200-1300{}^\circ C$.
So, the correct answer is “Option C”.

Note: The substance (atom, ion, and molecule) that gains electrons and is thereby reduced to a low valency state is called Oxidising agent.The substance that loses electrons and is thereby oxidised to a higher valency state is called a reducing agent.