Anode: Zinc electrode
Cathode: `SHE`
Cell: Zinc electrode `||SHE`
`E_(cell) = E_(H^(+)//H_(2)(g))-E_(Zn2+//Zn)^(@)`
`0.76V` (at `298K` experimentally)

Explanation

`E_(Zn2+//Zn)^(@) =- 0.76 V(SRP)`
`E_(Zn//Zn2+(aq))^(@) = 0.76 V(SOP)`
(b) Calomel Eolectrode:
`Hg(l)//Hg_(2)CI_(2)(s)//CI^(-)(aq)`
It is prepared by a `Pt` wire in contact with a paste of `Hg` and `Hg_(2)CI_(2)` present in a `KCI` solution.
reaction `(1)/(2)Hg_(2)CI_(2)(s) +e^(-) rarr Hg(l) +CI^(-)`.
`rArr E_(CI^(+)//Hg_(2)CI_(2)//Hg) = E_(H_(2)^(2)//Hg^(@)) +(0.059)/(2)log.(Ksp)/([CI]^(2)]`.
Like all metal-insoluble salt-anion electrodes, calomel electrode works at nearly constant potential for singnificant time.