Ethylene is an odorless, colorless, flammable gas with the chemical formula C2H4. It is the simplest alkene and is used in the production of many industrial chemicals. METHANE is a colorless, odorless, flammable gas with the chemical formula CH4. It is the main component of natural gas and is used as a fuel source. Silicane is a colorless, odorless, flammable gas with the chemical formula SiH4. It is a silicon-based analogue of METHANE and is used in the production of semiconductors. All three gases are colorless, flammable, and have no odor.