Q 1 :    

The correct option for a redox couple is                      [2023]

  • both are oxidised forms involving same element

     

  • both are reduced forms involving same element

     

  • both the reduced and oxidized forms involve same element

     

  • cathode and anode together.

     

(3)

In redox couple, both the reduced and oxidised forms involve same element.
 

 



Q 2 :    

Consider the change in oxidation state of bromine corresponding to different emf values as shown in the given diagram:

[IMAGE 43]

Then the species undergoing disproportionation is                 [2018]

  • BrO3-

     

  • BrO4-

     

  • Br2

     

  • HBrO

     

(4)

For a reaction to be spontaneous, Ecell should be positive as ΔG°=-nFEcell

HBrOBr2  ;  E°=1.595 V, SRP (cathode)

HBrOBrO3-  ;  E°=-1.5 V, SOP (anode)

2HBrOBr2+BrO3-

Ecell=SRP (cathode)-SRP (anode)

         =1.595-1.5=0.095 V

Ecell>0ΔG°<0 (spontaneous)