Question

When we connect a potato to a cell, the part connected to the positive terminal has green coloration. Why is it only on the part connected to the positive terminal and not on the negative side?

Answer 1

In this case, electrons from the negative terminal of the battery move inside potato as the copper wire inserted in potato undergoes electrolysis. This electrolysis is conducted in presence of starch present in potato. This process produces more electrons. When these electrons move from the negative terminal to the positive terminal, they react with the copper wire inserted in potato to form a bluish-green complex. Hence the colour at the positive terminal.