Advanced Placement (AP) Biology Practice Exam

What is the primary property of hydrocarbons?

1. They are polar and soluble in water

2. They consist solely of carbon and nitrogen

3. They are stable and nonpolar

4. They have a high density

The correct answer is: They are stable and nonpolar

Hydrocarbons are primarily composed of carbon and hydrogen atoms, resulting in a molecular structure that lacks significant electronegative atoms like oxygen or nitrogen. This characteristic leads to hydrocarbons being nonpolar molecules, meaning they do not have a charge separation across their structure. The absence of polar functional groups contributes to their stability, as they typically do not readily react with polar solvents like water. Additionally, their nonpolarity renders hydrocarbons hydrophobic, resulting in low solubility in water while making them suitable for energy storage in organisms.