Natural gas is colorless and odorless. The reason natural gas smells is because a smell is added to it before it is delivered to the consumer. The reason for the added smell is to draw awareness to a gas leak.
Propane
It is a colourless gas.
yes. it is colourless
Oxygen is a gas, therefore it is colourless.
Yes. argon is a colourless, odourless, noble gas.
Helium is a light colourless gas that does not burn
Colourless, or slightly white
Yes.
NO-gas is colourless
Helium is a colourless gas
Colourless gas
air