The major source(s) of chlorofluorocarbons (CFCs) in the atmosphere was/were ________
A) microbial fermentation of organic matter in coal mines, oil wells, and livestock
B) combustion of fossil fuels
C) refrigerants, solvents, and spray propellants
D) burning of fossil fuels and coal
E) emissions from automobile exhaust and chemical fertilizers
C
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Which of the following is NOT involved in turning some sediment into sedimentary rock?
A. compaction B. cementation C. metamorphism D. burial E. All of these are involved.
Brown-headed Cowbirds lay their eggs in other birds' nests, relying upon another species to raise their chicks. Although many species continue to raise the cowbird chicks, some species reject the eggs and offspring
Further, Brown-headed Cowbirds are rare inside large forests. Which of the following probably represents an adaptation in response to this cowbird threat? A) fewer breeding birds of other species rejecting cowbird chicks B) breeding birds of other species nesting in deep forests C) breeding birds of other species attracting cowbird adults to their region D) breeding birds of other species changing to a different type of bird song
Many African rivers do not have bridges for transportation across them, so they rely on ferry boats. Traffic jams and bottlenecks at these crossings can be backed up and take several days to clear
Indicate whether the statement is true or false
Which of the following methods of producing electricity have the lowest net energy ratios?
a. nuclear power and photovoltaics b. nuclear and wind power c. wind power and coal d. coal and hydroelectric e. nuclear and coal