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

What is true about alkenes?

1. They are saturated hydrocarbons

2. They contain at least one carbon-carbon single bond

3. They are unsaturated hydrocarbons with at least one carbon-carbon double bond

4. They contain no functional groups

The correct answer is: They are unsaturated hydrocarbons with at least one carbon-carbon double bond

Alkenes are defined as a category of hydrocarbons that are characterized by the presence of at least one carbon-carbon double bond. This double bond is what makes alkenes unsaturated, meaning they contain fewer hydrogen atoms compared to saturated hydrocarbons, which only have single bonds between carbon atoms. The unsaturation allows alkenes to undergo various chemical reactions, such as addition reactions, which is a hallmark of their reactivity. In contrast, other choices describe properties that do not apply to alkenes. For instance, saturated hydrocarbons, which contain only single bonds, refer to alkanes rather than alkenes. The mention of carbon-carbon single bonds is also not accurate when discussing alkenes, as their defining feature is the double bond. Furthermore, while alkenes do contain functional groups related to the double bond's properties, they are not devoid of functional groups; thus, the statement regarding the absence of functional groups does not hold true. Therefore, the assertion that alkenes are unsaturated hydrocarbons with at least one carbon-carbon double bond accurately reflects their chemical structure and properties.