ESCO Gas Furnace Practice Exam

Liquefied petroleum gases (LPG) primarily refer to the hydrocarbons propane and butane. These gases are found in a gaseous state at normal atmospheric pressure but can be easily liquefied under pressure, which is why they are classified as 'liquefied.' Propane is commonly used for heating, cooking, and as a fuel for engines, while butane is often used in portable stoves and lighters. Together, they comprise the primary components that make up LPG blends used in various applications.

The other gases listed do not fall under the category of liquefied petroleum gases. Methane and ethane are classified as natural gases rather than LPG. Hydrogen and oxygen are elemental gases and do not have the properties required to be categorized as liquefied petroleum gases. Although isobutane and isopropane may sound similar to propane and butane, isopropane (or isopropyl alcohol) is not classified as a gas in the context of LPG. Thus, the accurate classification as liquefied petroleum gases is specifically held by propane and butane.