What are the terms for single bonds and double bonds in hydrocarbon tails?

• A. Single bonds are unsaturated and double bonds are saturated
• B. Single bonds are saturated and double bonds are unsaturated
• C. Both are saturated
• D. Both are unsaturated

Answer: (B)

In hydrocarbon tails, saturation describes how many carbon–carbon bonds are single bonds. Tails with only single bonds can hold the maximum number of hydrogens, so they are called saturated. When a tail has one or more carbon–carbon double bonds, it has fewer hydrogens attached and is called unsaturated. The double bonds also create kinks that prevent tight packing, leading to lower melting points and making unsaturated fats typically liquid at room temperature, while saturated fats are more solid. So single bonds correspond to saturated, and double bonds correspond to unsaturated.