The standard reduction potential for `Zn^(2+)//Zn, Ni^(2+)//Ni` and `Fe^(2+)//Fe` are `-0.76, -0.23` and `-0.44V` respectively. The reaction `X + Y^(2) rarr X^(2+) + Y` will be spontaneous when:

Options

A. `X=Ni, Y=Fe`
B. `X=Ni, Y=Zn`
C. `X=Fe, Y=Zn`
D. `X=Zn, Y=Ni`

Answer

D

Explanation

For spontaneous process,
`E^(@)=E_("Reduced species")^(@)-E_("Oxidised species")^(@),` should be positive
`E^(@)=E_(Ni^(2+)//Ni)^(@)-E_(Zn^(2+)//Zn)^(@)`
`=-0.23-(-0.76)`
`=+0.53 V`