Why isn't manganese mined on the seabed when there are abundant manganese nodules in some parts of the ocean floor?
A) The manganese market is held by a global cartel who prevent the material from being mined.
B) It is not economical to mine manganese nodules at present-day world prices for manganese and associated metals in nodules.
C) The manganese is too difficult to extract from the nodules; a new technology is needed.
D) It is impossible to extract the nodules from the seafloor with present-day technology.
B
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During dry periods, most of the water flowing into streams is supplied by
A) overland flow. B) groundwater. C) rainfall. D) storms.
The type of metamorphism that occurs over large areas, commonly at convergent plate margins, and is
responsible for the production of most metamorphic rocks is ____________________. Fill in the blank(s) with the appropriate word(s).
Which of the following statements about malaria is true?
A) Malaria is the greatest health threat to northern Eurasia and North America. B) Mosquito saliva transmits tiny sporozooites to the victim when they are bitten. C) The organism that causes malaria is a virus related to H5N1. D) Malaria can be transmitted to humans by contact with pig or bird feces.
A watershed is ________
A) an inland basin that connects to another inland basin B) the water held in the atmosphere prior to returning to Earth in the form of rainfall C) a river that drains into the sea D) the area of land from which rainfall drains into rivers or lakes E) a term used to describe water stored underground