Which of the following most likely happens during a chemical change? no new substances are formed. properties of a substance remain unchanged. composition of a substance is same as before. different atoms than before are introduced after the change.

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).