85. Solving a chemistry problem

7. One or two electrodes may participate in the process of ketone reduction. The limiting diffusion current for a 1.0*10-3 M ketone solution is 6.80 μA. The diffusion coefficient is 5*10-6 cm2*sec-1, the mass of mercury flowing out of the capillary in 1 sec is 2 mg/sec, the dripping period is 5 sec. Calculate the number of electrons.