Which element has the highest electrode potential among the following?

To determine which element has the highest electrode potential, it's essential to understand that standard electrode potential values reflect how readily an element can be reduced, and thus, how easily it can gain electrons. Typically, greater electrode potentials are associated with elements that do not readily lose electrons and can more easily attract and hold onto them.

In this context, potassium (K) has a highly negative standard electrode potential, indicating it is very willing to lose electrons (be oxidized). Therefore, it is not one of the elements with the highest electrode potential.

Mercury (Hg), on the other hand, has a positive standard electrode potential, indicating it can gain electrons more easily and is more likely to be reduced compared to potassium and the other metals listed. This reflects its tendency to stabilize in a reduced form.

Chromium (Cr) and magnesium (Mg) also exhibit negative standard electrode potentials, indicating a stronger tendency to lose electrons compared to mercury.

Thus, mercury stands out as having the highest electrode potential among the elements listed, leading to its correct identification in this scenario.