Which of the following is an advantage of solar power as a source of electricity?

a. it uses a free energy source that will not run out.
b. it is less expensive than most other kinds of fuel.
c. it works equally well in every kind of weather.
d. it depends on nontoxic materials for solar cells.

the correct answer is a.

The lines marked by the letters a, b, and c on the map above represent a. chains of volcanoes b. earthquake fault lines c. thin strips of heavy forests d. major rivers that flow from north to south

Which statement best explains distribution of natural resources? people tend to settle in locations that have the resources they need for survival. some countries have resources that others lack, so trade between countries becomes vital. fossil fuels come from areas that have mountains and other areas that manufacture synthetic gas. areas with natural resources provide a higher standard of living and better quality of life.

In the following diagram, four different index fossils are labeled: which of the labeled fossils comes from the oldest organism? a b c d