3. Plot the Butler-volmer equation using alfa=0.5 and 0.2, respectively. For each, please zoom in for small overpotential and zoom out for large overpotential. 4. Plot the I-V of PEM fuel cell at different io, il, and R_ohm, and compare. Please use below as a reference curve: E,=1.23V b=60mV, 10=10-0.7Acm2 r=0.232cm2 5. Please estimate the limiting currents (due to oxygen transport through the MPL) for pure oxygen and air at 1 atm, and air at 2 atm. Assuming the diffusivity is 1x10-6 m/s and the MPL thickness is 50 micro meter. 6. Please plot the Nafion membrane water content as a function of water activity in the range of 0-1. (see Wang, Y., & Wang, C. Y. (2006) A nonisothermal, two- phase model for polymer electrolyte fuel cells. Journal of the electrochemical society, 153(6), A1193-A1200). 7. Please the model to plot the water diffusion coefficient as a function of water activity in Nafion (see Wang, Y., & Wang, C. Y. (2006)). 8. Please use Wang et al 2010 model to plot Nafion's proton conductivity as a function of T from -40 - 0 C and water content (see Wang, Y., Mukherjee, P. P., Mishler, J., Mukundan, R., & Borup, R. L. (2010). Cold start of polymer electrolyte fuel cells: Three-stage startup characterization. Electrochimica Acta, 55, 2636-2644.) 9. Please plot Pc as a function of s using the Leverett function for the GDL of contact angle =80, 120 and 150 (using the parameters in Wang, Y., & Wang, C. Y. (2006))