Question

For the feasibility of a redox reaction in a cell, the emf should be

• A. Fixed
• B. Positive
• C. Zero
• D. Negative

Answer 1

Answer: (B)

Any redox reaction would occur spontaneously if the free energy change ($\Delta G$) is negative.
$\Delta G^{°}=-nF{E}^{°}$
Where $n$ is the number of electrons involved, $F$ is the value of Faraday and $E^{°}$ is the cell emf. $\Delta G^{°}$ can be negative if $E^{°}$ is positive.