Equilibrium constant K is related to `E_("cell")^(@)` and not `E_("cell")` because

Options

A. `E_("cell")^(@)` is easier to measure than `E_("cell")`
B. `E_("cell")` becomes zero at equilibrium point but `E_("cell")^(@)` remains constant under all conditions
C. At a given temperature, `E_("cell")`changes hence value of K can not be measured
D. Any of the terms `E_("cell")` or `E_("cell")^(@)` can be used

Answer

B