What will be the emf for the given cell ?
`Pt|H_(2)(g,P_(1))|H^(+)(aq)|H_(2)(g,P_(2))|Pt`

Options

A. `(RT)/(F) log_(e) (P_(1))/(P_(2))`
B. `(RT)/(2F) log _(e) (P_(1))/(P_(2))`
C. `(RT)/(F) log_(e) (P_(2))/(P_(1))`
D. None of these

Answer

B

Explanation

`RHS : 2 H^(+) + 2e^(-) hArr H_(2) (P_(2))`
LHS `: H_(2) (P_(1)) hArr 2 H^(+) + 2e^(-)`
Overall reaction : `H_(2) (P_(1)) hArr H_(2) (P_(2))`
`E = E^(@) - (RT)/(nF) "ln" (P_(2))/(P_(1)) = 0 - (RT)/(nF)"ln" (P_(2))/(P_(1)) = (RT)/(nF) "ln" (P_(1))/(P_(2))`