Question

During the electrolysis of fused NaCl, the reaction at anode is:
A.$C{l^ - }$ ions are oxidised
B.$C{l^ - }$ ions are reduced
C.$N{a^ + }$ ions are oxidised
D.$N{a^ + }$ ions are reduced

Answer 1

Hint: Oxidised: The substance which takes oxygen or loses hydrogen during the reaction, is known as oxidised. Or we can say that the molecule or atom which loses one or more electrons, is known as an oxidised molecule.
Reduced: The substance which loses oxygen or takes hydrogen during the reaction, is known as reduced molecule. Or we can say that the molecule or atom which gains one or more electrons, are known as a reduced molecule.

Complete step by step solution:
First of all let us talk about oxidised and reduced compounds.
Oxidised: The substance which takes oxygen or loses hydrogen during the reaction, is known as oxidised. Or we can say that the molecule or atom which loses one or more electrons, is known as an oxidised molecule.
Reduced: The substance which loses oxygen or takes hydrogen during the reaction, is known as reduced molecule. Or we can say that the molecule or atom which gains one or more electrons, are known as a reduced molecule.
When an electric current is passed through a concentrated solution of sodium chloride salt then hydrogen gas will be evaluated at the negative electrode i.e. cathode, and chlorine gas will be formed at positive electrode i.e. anode.
At anode the reaction is as: $2C{l^ - } \to C{l_2} + 2{e^ - }$.
Here chlorine atom loss electron so it acts as an oxidised compound.
And the reaction at cathode will be:
$2{H^ + } + 2{e^ - } \to {H_2}$
Here hydrogen atoms gain electrons hence it acts as a reduced compound.
At anode (positive electrode) oxidation will occur and at the cathode (negative electrode) reduction will occur.

Hence option A i.e. $C{l^ - }$ ions are oxidised is correct.

Note:
Oxidation number of an element: It is defined as the total number of electrons that an atom accepts or loses in order to make a chemical bond which results in the formation of a chemical compound.