Which minerals are most important? (2.7)
What will be an ideal response?
Answer: Minerals are most important if they are common in rocks, provide essential resources, or both. Silicate minerals are the primary rock-forming minerals in the crust. More than 4,000 minerals have been identified, but only a few dozen are important as rock-forming minerals, because only 12 of the 89 naturally occurring elements compose 99.7 percent of Earth's crust. However, most economically valuable metals are processed from nonsilicate ore minerals, especially oxide and sulfide minerals, so not only silicate minerals are important!
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Rocks that were formerly part of Laurentia are now mostly in ____
a. North America b. South America c. Europe
d. Africa e. Antarctica
Which of the following statements about shifting cultivation is most accurate?
A) Shifting cultivation is not sustainable. B) Shifting cultivation is sustainable. C) Shifting cultivation can be sustainable if the population is small enough for the land area available for this agricultural system. D) Shifting cultivation is no longer practiced. E) Shifting cultivation is usually practiced in the middle latitudes.
For which of the following reactions is it important that the species collide with the correct orientation?
A) HCl(g) + H2O(l) ? H2O+(aq) + Cl-(aq) B) Ag+(aq) + Cl-(aq) ? AgCl(s) C) both of them D) neither of them
Vitamin A deficiencies are associated with
A. Blindness B. Poorly developed neural systems in embryos C. Weak bones D. A lack of energy, or listlessness E. Anemia