Answer: Peer-reviewed journal article is the most useful because the information in them had been carefully scrutinized and aproved by people who are experts in that particular field.
This statement is false due to the fact that the ammonia gas has the lower molar mass.
The correct answer would be equation 4, because there are 4 Hydrogens and 2 Oxygens on each side of the equation making it balanced.
The answer is Hydrogen
This is what happens when acids react with metals