The calcium in a 200 mL sample of a natural water was determined by precipitating the cation as CaC2O4. The precipitate was filtered, washed and ignited in a crucible with an empty mass of 26.6002 g. The mass of the crucible plus CaO (M.W 56.077 g/mol) was 26.7134 g. Calculate the concentration of Ca (MW40.078 g/mol) in the water in units of gram per 100 mL.