How much of earth's atmosphere is made up of nitrogen and oxygen?
a. 100 percent
b. between 25 and 75 percent
c. close to 99 percent
d. less than 1 percent

The district of columbia could be eliminated completely if a majority of congress voted in favor of the action. a. true b. false

17. the soil erosion pictured here is the result of what? a. harvesting renewable resources at a rate greater than the sustainable yield b. a mudslide caused by excessive rains c. harvesting renewable resources at a rate lower than the sustainable yield d. the transition between geologic eras and eons

What type of coastline is commonly found along the western side of the america’s