At standard temperature and pressure (STP), carbon is a solid, so it would be denser than air at STP.
Some are heavier, but some are lighter. For example, methane rises but propane sinks.
Because, carbon dioxide is heavier than air whereas helium is lighter than air.
Just, simply, Lighter than Air Vehicles are lighter than air, so that makes them fly, and Heavier than air vehicles are heavier than air, but they use airfoils on the wings to fly.
Greenhouse gasses are NOT "obviously lighter than air"; carbon dioxide is significantly heavier than air.One way to weigh something that's lighter than air is to weigh it in a vacuum.
Nitrous Oxide is heavier than air.
Helium is lighter than air
Carbon MONOXIDE is lighter than air, and will rise. Place the detector high. Carbon DIOXIDE is heavier than air, and will sink. Place detector low.
Xenon is more than 4.5 times heavier than air.
Oxygen. Because , mass of carbon monoxide is 28, whereas that of oxygen is 32.
Natural gas is lighter than air and rises.
One is lighter and the other one is heavier. :D
Moist air is heavier than dry air, because of the water.