Each box contains 10 items. Box 1
Net mass A = 10 grams
Box 2
Net mass B = 5 grams
Box 3
Each made of 1 A and 1 B

Mass box A = 10 grams; Mass box B = 5 grams; Mass box C-made of one A and one B
Mass ratio A/B =

Butane gas reacts with oxygen gas to give carbon dioxide gas and water vapor (gas). if you mix butane and oxygen in the correct stoichiometric ratio, and if the total pressure of the mixture is 390 mmhg, what is the pressure (in mmhg) of water vapor after the reaction is completed (temperature and volume do not change).