| A | B |
|---|
| natural resources | any natural substance, organism, or energy form that living things use |
| renewable resource | a natural resource that can be used and replaced over a relatively short time |
| nonrenewable resource | a natural resource that cannot be replaced or that can be replaced only over thousands or millions of years |
| recycling | the process by which used or discarded materials are treated for reuse |
| energy resource | a natural resource that humans use to produce energy |
| fossil fuel | a nonrenewable energy resource that forms in the Earth's crust over millions of years from the buried remains fo once-living organisms |
| petroleum | an oily mixture of flammable organic compounds from which liquid fossil fuels and other products are separated; crude oil |
| natural gas | a gaseous fossil fuel |
| coal | a solid fossil fuel formed underground from buried, decomposed plant material |
| strip mining | a process in which rock and soil are stripped from the Earth's surface to expose the underlying materials to be mined |
| acid precipitation | precipitation that contains acids due to air pollution |
| smog | a photochemical fog produced by the reaction of sunlight and air pollutants |
| nuclear energy | the form of energy associated with changes in the nucleus of an atom; an alternative energy resource |
| solar energy | energy from the sun |
| wind energy | energy from the wind |
| hydroelectric energy | electricity produced by falling water |
| biomass | organic matter, such as plants, wood and waste that contains stored energy |
| gasohol | a mixture of gasoline and alcohol that is burned as a fuel |
| geothermal energy | energy from within the Earth |
