Hydrocarbons usually do not mix in water because they are __________.

• A. Polar
• B. Charged
• C. Non-polar
• D. Hydrophilic

Answer: (C)

Solubility hinges on polarity. Water is a polar molecule that forms strong hydrogen bonds, so it interacts best with other polar or charged substances. Hydrocarbons, on the other hand, are nonpolar because the carbon and hydrogen atoms share electrons fairly evenly, giving little partial charge. When a nonpolar substance tries to mix with water, it can’t form favorable interactions with the water molecules and would disrupt water’s hydrogen-bond network. That disruption costs energy, so the system favors separating into distinct phases rather than mixing. This is why hydrocarbons are immiscible in water and are described as nonpolar and hydrophobic.