Petroleum is a complex mixture of compounds known as ______.

Explanation

**Step-by-Step Solution:**

1. **Understanding Petroleum**: Petroleum is a natural resource that is found deep beneath the Earth's surface. It is formed from the remains of ancient marine organisms that have been subjected to heat and pressure over millions of years.

2. **Composition of Petroleum**: Petroleum is not a single compound; rather, it is a complex mixture. This mixture primarily consists of various types of hydrocarbons, which are compounds made up of hydrogen and carbon atoms.

3. **Types of Hydrocarbons**: The hydrocarbons in petroleum can be classified into different states, including gaseous, liquid, semi-solid, and solid forms. This diversity in physical state contributes to the various uses of petroleum in fuels, lubricants, and other chemical products.

...