The standard electrode potentials of some electrodes are : `{:("Electrode",Zn^(2+)"|"Zn,Cd^(2+)"|"Cd,Ag^(+)"|"Ag,Fe^(2+)"|"Fe),(E^(@)(V),-0.76,-0.40,0.80V,-0.44V):}`
Which of the following cells are feasible and give their `E^(@)` cell ?
(i) `Zn|Zn^(2+)||Cd^(2+)|Cd`
(ii) `Fe|Fe^(2+)||Zn^(2+)|Zn`
(iii) `Cd|Cd^(2+)"||"Ag^(+)`
(iv) `Fe|Fe^(2+)"||"Ag^(2+)|Ag`

Options

A. (i) , (iii) , (iv)
B. (i) , (iii)
C. (ii)
D. (ii) , (iv)

Answer

A

Explanation

(i) Feasible ,`E^(@)=+0.36V`
(ii) Not feasible , `E^(@)=-0.32V`
(iii) Feasible ,`E^(@)=+1.20V`
(iv) Feasible , `E^(@)=+1.24V`
so, option (A) us correct