___________ ______________ are substances made through the conversion of petroleum or coal.

Synthetic Substances

Artificial materials created through chemical processes, not found naturally.

Coal

A natural, black or brownish-black sedimentary rock used primarily as a fuel source in electricity generation and steel production.

Petroleum

A liquid mixture of hydrocarbons that is present in certain rock strata and can be extracted and refined to produce fuels including gasoline, kerosene, and diesel oil.