What is crude oil a mixture of?

Crude oil is primarily a complex mixture of different length hydrocarbon molecules. These hydrocarbons range from very short-chain molecules, like gases, to long-chain molecules, which can be found in liquid form or as waxy solids. The varying lengths of the hydrocarbon chains contribute to the distinct properties of the different components found in crude oil, such as viscosity, boiling point, and the ease of combustion.

The hydrocarbons present in crude oil are also crucial as they serve as the source material for fuels and chemicals in various industrial processes. This mixture's complexity is a key characteristic that allows for the separation of its components through processes like fractional distillation, leading to valuable products such as gasoline, kerosene, and diesel.

The other options do not accurately define crude oil; for example, while gases and liquids may be part of the mixture, crude oil itself is not simply a collection of gases and liquids together.