Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

Which type of hydrocarbon is always saturated?

1. Alkene

2. Alkyne

3. Aromatic hydrocarbon

4. Alkane

The correct answer is: Alkane

The type of hydrocarbon that is always saturated is the alkane. Saturated hydrocarbons are those that contain only single bonds between carbon atoms. This means that each carbon atom in an alkane is bonded to as many hydrogen atoms as possible, resulting in the maximum number of hydrogen atoms for a given number of carbon atoms. Alkanes have the general formula CnH2n+2, which reflects their saturated nature. Since all the bonds between carbon atoms are single bonds, there are no double or triple bonds present, which distinguishes alkanes from alkenes and alkynes. Alkenes contain at least one double bond, while alkynes contain at least one triple bond, meaning neither can saturate the carbon atoms with hydrogen to the maximum extent. Aromatic hydrocarbons, although they have a stable structure, often contain alternating double bonds and are not considered saturated. Thus, the saturation characteristic of alkanes is what makes them unique among these types of hydrocarbons, confirming why this choice is the correct answer.