What is the main obstacle to extracting rare-earth metals from a deposit?
A. They are typically found at low concentrations in the host rock.
B. They are equally distributed around the world.
C. There is a lack of technological understanding about how to extract them.
D. There is no demand for them on the world market.
Answer: A
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Which of the following gives the name for the small, smooth cloud that may form just above the top of a towering cumulus cloud?
A. banner cloud B. contrail C. mammatus cloud D. pileus cloud
Where are the enzymes which promote the reaction 4H+ + 4e- + O2 ? 2H2O located?
A) in the cytoplasm B) embedded in the inner membrane of the mitochondria C) embedded in the outer membrane of the mitochondria D) embedded in the matrix
Why is there salt in the oceans?
A. Precipitation B. Runoff from the continents C. Comets D. Melting of ice at the Poles
Compared with the other Group C types, what distinguishes marine west coast climates?
A. They don’t occur in the midlatitudes. B. They receive more solar radiation. C. They are typically the driest of all C climates. D. They receive onshore flow of westerlies. E. They provide very little cloud cover.