| A | B |
|---|
| natural resource | any natural material that is used by humans (water, petroleum, etc.) |
| renewable resource | a natural resource that can be replaced at the same rate as the resource is used |
| nonrenewable resource | a resource that forms at a rate that is much slower than the rate at which it is used |
| recycling | the process of recovering valuable or useful materials from waste |
| fossil fuel | a nonrenewable energy resource formed from the remains of organisms that lived long ago |
| chemical energy | the energy released when a chemical compound reacts to produce new compounds |
| natural gas | a mixture of gaseous hydrocarbons located under the surface of the Earth |
| coal | a fossil fuel that forms underground from partially decomposed plant material |
| acid precipitation | precipitation (rain, sleet, or snow) that contains a high concentration of acids |
| smog | photochemical haze that forms when sunlight acts on industrial pollutants are burning fuels |
| nuclear energy | the energy released by fission or fusion reaction |
| petroleum | a liquid mixture of complex hydrocarbon compounds |
