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 = Zn
B. X = Fe, Y = Zn
C. X = Z, Y = Ni
D. X = Ni, Y = Fe

Answer

C

Explanation

The elements with high negative value of standard reduction potential are good reducing agents and can be easily oxidized.
The X should have high negative value of standard potential than Y so that it will be oxidised to `X^(2+)` by reducing `Y^(2+)` to Y.
X = Zn, Y = Ni
Alternatively, for a spontaneous reaction `E^(@)` must be positive.
`E^(@)=E_("reduced species")^(0)-E_("oxidized species")^(0)`
`rArrE^(@)=+0.53V`