GED Science Practice Test 2026 [Timed 90 Minutes – 35 Questions]

Questions 3 through 5 are based on the following information. Coal is formed from the material of plants and other organisms that lived on land and whose remains were covered by mud, which later became rock. Coal is classified by carbon content. Peat = The remains of plants and organisms that, because they were covered in bogs, were prevented by a lack of oxygen from completely decaying. Still a porous, soft brown mass, peat has a carbon content of 52%–60%. Lignite = In time, peat turns into lignite, a soft coal-like substance that is 60%–65% carbon. Subbituminous coal = With more time, heat, and pressure, lignite changes into subbituminous coal, which is about 65%–75% carbon. Bituminous coal = After even more heat and pressure, subbituminous coal turns into bituminous coal with a carbon level of 75%–85%. Anthracite = This is bituminous coal subjected to another million years of heat and pressure. Anthracite has a carbon level of 85%–95% and will burn only at extremely high temperatures. A researcher analyzes a piece of coal and finds that it is unusually dense and burns only when subjected to very intense heat. What is the lowest percentage of carbon that this coal is likely to contain? Enter the _____ %.