The magnitude `(` but not the sign `)` of the standard reduction potentials of two metals `X` and `Y` are `:`
`Y^(2)+2e^(-) rarr Y |E_(1)^(c-)|=0.34V`
`X^(2)+2e^(-) rarr X |E_(2)^(c-)|=0.25V`
When the two half cells of `X` and `Y `are connected to construct a cell, eletrons flow from `X` to `Y`. When `X` is connected to a standard hydrogen electrode `(SHE)`,electrons flow from `X` to `SHE`.
If standard emf `(E^(c-))` of a half cell `Y^(2)|Y^(o+)` is `0.15V`, the standard emf of the half cell `Y^(o+)|Y` will be

Options

A. `0.19V`
B. `0.53V`
C. `0.49V`
D. `0.64V`

Answer

b

Explanation

Also,
`{:(Y^(o+)+e^(-)rarr Y(s),,,=,E^(c-)._(req)=?),(,,,implies,DeltaG^(c-)._(req)=-1xxFxxE^(c-)._(req)):}`
` {:(Y^(2+)+e^(-)rarrY^(o+),,,=,E^(c-)._(1)=0.15V),(,,,implies,DeltaG^(c-)._(1)=-1xxFxxE^(c-)._(1)):} `
` {:(Y^(2+)+e^(-)rarrY(s),,,=,E^(c-)._(2)=0.34V),(,,,implies,DeltaG^(c-)._(2)=-2xxFxxE^(c-)._(2)):} `
` {:(ulbar(Y^(2+)+e^(-)rarrY(s)),,,=,-FE^(c-)._(req)=-2FE^(c-)._(2)-(-FE^(c-)._(1))),(,,,implies,E^(c-)._(req)=-2E^(c-)._(2)-E^(c-)._(1)):} `
`=2(0.34)-0.15`
`=0.53V`