Standard electrode potential for `Sn^(4+)//Sn^(2+)` couple is `0.15 V` and that for the `Cr^(3+)//Cr` couple is `-0.74 V`. These two couples in their standard state are connected to make a cell. The cell potential will be

Options

A. `+1.83 V`
B. `+1.19 V`
C. `+0.89 V`
D. `+0.18 V`

Answer

D

Explanation

`Sn^(4+)(aq.)+2e^(-) rarr Sn^(2+)(aq.), E^(@)= +0.15`
`Cr^(3+)(aq.)+3e^(-) rarr Cr(s), E^(@)= -0.74 V`
The one which ahd higher reduction potential plays the role of cathode.
`E_("cell")^(@) = E_(R)^(@)-E_(L)^(@)`
`= (+0.15 V)-(-0.74 V)`
`= +0.89 V`