Question

Lose of electrons and gain of electrons are respectively called as
A. reduction and oxidation
B. oxidation and reduction
C. reduction alone
D. oxidation alone

Answer 1

Hint: A species loses or gains electrons to form a bond with another. The species which lose electrons get oxidized. The species which gain electrons get reduced.

Complete answer
By the loss of electrons, a cation forms and by the gain of electrons, an anion forms. The loss of electrons is known as oxidation and the gain of electrons is known as reduction. The species which loses electrons goes under the oxidation process and the atom which gains electrons goes under the reduction process.
The species which lose electrons cause another species to accept electrons, so the species which lose electrons is known as reducing species. The species which gain electrons cause another species to lose electrons, so the species which gain electrons is known as oxidizing species.

An example of the oxidation and reduction reaction is as follows:
${\text{Zn}}\,{\text{(s) + }}\,{\text{CuS}}{{\text{O}}_{\text{4}}}\,{\text{(aq)}}\, \to {\text{Cu(s) + }}\,{\text{ZnS}}{{\text{O}}_{\text{4}}}\,{\text{(aq)}}\,$

In this reaction, zinc metal loses electrons, so the oxidation of zinc takes place and copper ion gains electrons, so the reduction of copper ion takes place. Here, the zinc metal is a reducing agent and the copper ion is an oxidizing agent.

The separate reduction and oxidation processes are as follows:
Oxidation of zinc: ${\text{Zn}}\,{\text{(s)}} \to {\text{Z}}{{\text{n}}^{2 + }}\,{\text{(aq)}}\, + 2{{\text{e}}^ - }\,$
Reduction of copper: ${\text{C}}{{\text{u}}^{2 + }}\,{\text{(aq)}}\, + 2{{\text{e}}^ - }\, \to {\text{Cu}}\,{\text{(s)}}$

Therefore, option (B) oxidation and reduction is correct.

Note: Oxidation is the release of the electrons and reduction is the acceptance of the electrons. Oxidation and reduction reactions are not independent, both take place simultaneously. The reaction in which electrons are transferred between two reactants is known as the redox reaction. The reaction between zinc and copper sulphate is an example of a redox reaction.