Multiple choice

The natural substance from which energy can be harnessed is essentially made up of only one element. It is

  1. petroleum

  2. coal

  3. water (in dams)

  4. air (in winds mills)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Coal is primarily composed of carbon, which is a single element. Petroleum is a complex mixture of hydrocarbons, while water and air are not elemental energy sources in the same sense.

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