To determine the concentration of the copper II ion Cu2+ solution using polarography, we need to use the Ilkovic equation. The Ilkovic equation is:i_d = n * D^1/2 * A * C * t/ ^1/2 where:i_d = diffusion current A n = number of electrons involved in the redox reaction for Cu2+/Cu, n = 2 D = diffusion coefficient cm^2/s A = electrode area cm^2 C = concentration of the analyte mol/cm^3 t = time s First, we need to find the limiting current i_l , which is the difference between the currents at -1.0 V and -0.5 V:i_l = 25 mA - 10 mA = 15 mA = 0.015 ANext, we need to find the diffusion coefficient D of Cu2+ in 0.1 M KCl. The diffusion coefficient of Cu2+ in 1 M KCl is approximately 7.2 x 10^-6 cm^2/s. Since the supporting electrolyte is 0.1 M KCl, we can assume that the diffusion coefficient remains roughly the same.Now, we need to find the electrode area A and the time t . Unfortunately, these values are not provided in the problem. However, we can still express the concentration C in terms of these unknown values:C = i_d / n * D^1/2 * A * t/ ^1/2 C = 0.015 A / 2 * 7.2 x 10^-6 cm^2/s ^1/2 * A * t/ ^1/2 C 0.015 A / 0.0054 A * t/ ^1/2 C 2.78 / t/ ^1/2 Without the values of electrode area A and time t , we cannot determine the exact concentration of the Cu2+ solution. However, we can express the concentration as a function of these unknown values, as shown above.