68. Solving a chemistry problem

7. A. Is it possible to oxidize Mn2 to MnO4- with potassium bichromate in an aqueous solution if its pH = 2, and the concentrations of other ions involved in the redox reaction are 1 mol/dm3?
B. An excess of potassium iodide was added to 25.00 cm3 of an acidified solution of potassium permanganate with a titer of 0.001836 g/cm3. 20.50 cm3 of sodium thiosulfate solution was used for titration of the released iodine. Determine the molar concentration of the Na2S2O3 equivalent in the titrant.