International General Certificate of Secondary Education (IGCSE) Chemistry Practice Exam

Which of the following is a property of crude oil?

1. It has a low viscosity

2. It has a high boiling point

3. It does not burn

4. It is a complex mixture of hydrocarbons

The correct answer is: It is a complex mixture of hydrocarbons

Crude oil is known as a complex mixture of hydrocarbons, which means it comprises various organic compounds primarily made of hydrogen and carbon atoms. This complexity arises because crude oil is naturally occurring and includes many different types of hydrocarbons, such as alkanes, cycloalkanes, and aromatic hydrocarbons, each with varying molecular weights and structures. This mixture is important because it determines the properties and behaviors of crude oil in different refining processes and applications. The other options do not accurately describe the properties of crude oil. For example, crude oil typically has a high viscosity, meaning it is thick and sticky, not low. Additionally, crude oil does have a range of boiling points; however, it is not accurate to categorize the boiling point as simply high or low because it varies depending on the specific hydrocarbons present. Finally, crude oil is combustible and can burn, contrary to the assertion that it does not burn. Thus, the defining characteristic of crude oil is that it consists of a complex mixture of hydrocarbons.