To calculate the current density of the electrochemical cell, we first need to find the current I flowing through the cell. We can use Ohm's law to do this:Ohm's law: V = I * RWhere V is the voltage, I is the current, and R is the resistance.Rearranging the formula to solve for I:I = V / RNow, we can plug in the given values:I = 0.65 volts / 50 ohmsI = 0.013 A amperes Next, we need to find the current density J . Current density is defined as the current per unit area. Since the nickel electrode is being oxidized, we will use the surface area of the nickel electrode to calculate the current density:J = I / AWhere J is the current density, I is the current, and A is the surface area of the nickel electrode.Plugging in the values:J = 0.013 A / 10 cmJ = 0.0013 A/cmSo, the current density of the electrochemical cell is 0.0013 A/cm.