Texas Compressed Natural Gas (CNG) Delivery Truck Driver Practice Exam

CNG, or Compressed Natural Gas, is primarily composed of natural gas, which is mainly methane (CH4) along with small amounts of other hydrocarbons and impurities. The term 'compressed natural gas' specifically refers to the natural gas that has been compressed to a fraction of its volume for use as fuel, making it more convenient for storage and transportation. Natural gas possesses properties that allow it to be efficiently compressed and stored in this form, making it suitable for use in vehicles designed for CNG. Other gases listed, such as propane, cyclopropane, and butane, have different physical and chemical characteristics and are classified as different types of hydrocarbons. While these gases can be compressed and used as fuels, they do not fall under the category of natural gas and are not referred to as CNG. Therefore, the correct answer highlights the specific source of the gas used in this context, which is natural gas itself.