For a cell reaction involving two electron change, the standard EMF of the cell is 0.295 V at ${25}^{0}C$. The equilibrium constant of the reaction at ${25}^{0}C$ will be

According to Nernst equation,

$E=E^0-\frac{0.059}{n}\log Qat{25}^{0}C$

At equilibrium, $E=0,Q=K$

$\therefore 0=E^0-\frac{0.059}{n}\log K\Rightarrow E^0=\frac{0.059}{n}\log K$

$\log K=\frac{E^0\times n}{0.059}\Rightarrow \log K=\frac{0.295\times 2}{0.059}$

$K=anti\log \frac{0.295\times 2}{0.059}\Rightarrow K=1\times {10}^{10}$