The standard reduction potential of Pb and Zn electrodes are -0.12 6 and -0.763 volts respectively . The e.m.f of the cell
`Zn|Zn^(2+)+(0.1M)||Pb^(2+)(1M)Pb` is

Options

A. 0.637 V
B. `lt` 0.637 V
C. `gt` 0.637 V
D. 0.889 V

Answer

A

Explanation

`E= E^(Theta) - (0.059)/(2) "log" ([Zn ^(2+)])/([Pb^(2+)])`
`E^(Theta) = E_((Pb^(2+) |Pb))^(Theta) - E_((Zn^(2+) //Zn))^(Theta)`
`= -0.126 - (-0.763) = 0.637 V`
`E = 0.637 - (0.059)/(2) log ((0.1))/((0.1))`
`= 0.637` V .