108. Solving a chemistry problem

489. A portion of sodium dichromate dihydrate weighing 1.5500 g was dissolved in dilute sulfuric acid and 100.0 ml of solution was obtained. An excess of potassium iodide solution was added to a 10 ml aliquot of the resulting solution, and 21.42 ml of sodium thiosulfate solution was used to titrate the isolated iodine. Calculate the molar concentration of sodium thiosulfate solution and its titrimetric conversion factor for hydrogen peroxide.