4076089go 4076089go Chemistry Answered The molar mass of an insecticide, dibromoethane, is 187.9 g/mol. Its molecular formula is C2H4Br2. What percent by mass of bromine does dibromoethane contain? OA) 42.52% OB) 2.14% OC) 85.05% OD) 12.78% E) 6.39%