28. Solving a chemistry problem

16th century The analyzed sample of Mohr´s salt weighing 0.3887 g was dissolved in dilute sulfuric acid, after which the potentiometric titration of iron(II) was carried out with a standard solution of cerium(IV) sulfate with a molar equivalent concentration of 0.04955 mol/l and the following results were obtained (V is the volume of added titrant, E is the EMF of the circuit):
V, ml 14.00 18.00 19.00 19.80 20.00 20.20 21.00 22.00 26.00
E, mV 736 780 810 877 1098 1320 1393 1424 1469
Calculate the mass fraction (%) of iron(II) in the analyzed sample, using the following method to determine the equivalence point (TE).
Which electrodes (platinum, calomel, silver chloride, glass) can be used as an indicator electrode, and which ones can be used as a reference electrode for this titration?
c) Graphical (Gran´s method) - along the titration curve * in the coordinates ΔV / ΔE-V