Molecules with 5 to 20 carbon atoms are typically in which physical state?

Molecules that contain between 5 to 20 carbon atoms are generally found in the liquid state at room temperature. This range includes many hydrocarbons, which are the building blocks of many fuels and oils. As the carbon chains increase in length, the molecules generally possess greater intermolecular forces such as van der Waals forces, which help maintain a liquid state due to the increased boiling and melting points.

For example, alkanes like pentane (5 carbons) are gases at room temperature, but as the number of carbon atoms increases, such as in decane (10 carbons) or dodecane (12 carbons), these substances transition into liquids. This trend continues, and by the time you reach higher carbon counts, they often remain liquid under standard conditions.

Longer chains beyond 20 carbons typically begin to solidify, but for the specified range of 5 to 20 carbon atoms, the vast majority are classified as liquids, aligning with the provided answer.