What is the standard cell potential for the reaction with $K=1$ (equilibrium constant)

For a first order reaction ( $A \rightarrow B$ ), the temperature ( $T$ ) dependent rate constant $(k)$ in $\mathrm{s}^{-1}$ was found to follow the equation $: \log k=\left(-\frac{20}{T}\right)+4$. The activation energy ( $E_a$ ) and pre-exponential factor ( $A$ ) respectively, are

The method, which is based on the principle that "different components of a mixture are differently adsorbed on an adsorbent" is called

The solubilities of the impurities in the melt and solid states is not same. This principle is applied during the extraction of boron. This method is known as