In which of the following salt bridge is not needed ?

Options

A. `Pb|PbSO_(4)(s)|H_(2)SO_(4)|PbO_(2)(s)|Pb`
B. `Cd|CdO(s)|KOH(aq)|NiO_(2)(s)|Ni`
C. `Fe(s)|FeO(s)|KOH(aq),Ni_(2)O_(3)(s)|Ni`
D. `Zn|ZnSO_(4)|CuSO_(4)|Cu`

Answer

a,b,c

Explanation

Salt bridge is used to eliminate liquid junction potential arised due to different speed of ions present in cathodic and anodic compartments.