Given:
`E_(Zn^(+2)//Zn)^(@) =- 0.76V`
`E_(Cu^(+2)//Cu)^(@) = +0.34V`
`K_(f)[Cu(NH_(3))_(4)]^(2+) = 4 xx 10^(11)`
`(2.303R)/(F) = 2 xx 10^(-4)`
At what concentration of `Cu^(+2)` emf of the cell will be zero (at 298K) and concentration of `Zn^(+2)` is remains same:

Options

A. `1.19xx10^(-37)`
B. `1.19xx10^(-20)`
C. `3.78xx10^(-4)`
D. `0.0068`

Answer

A