2H + O 2HO 15. The reaction of hydrogen and oxygen gas to produce water is shown above. Suppose 10.0 grams of hydrogen are mixed with 32.0 grams of oxygen, what is the limiting reagent and how many excess grams of the other is left at the end of the reaction? (Molar masses: H = 2.0 g/mol; O = 32.0 g/mol) (A) Limiting reagent = hydrogen; Excess = 16.0 grams of oxygen (B) Limiting reagent = hydrogen; Excess = 22.0 grams of oxygen (C) Limiting reagent = oxygen; Excess = 6.0 grams of hydrogen (D) Limiting reagent = oxygen; Excess = 8.0 grams of hydrogen