Our Earth has many resources, but they are not unlimited. In the ...

[Jipu 123]

Our Earth has many resources, but they are not unlimited. In the case of abundant metals, supply will most often meet demand. However, problems can occur when
 
  A) there is a shortage of ores that can be mined at a reasonable cost.
  B) high grade ores are depleted and low-grade ores need to be mined.
  C) transport and processing costs override economic feasibility.
  D) all of the above.

Question 2

The melting point of silicate minerals is strongly dependent on the amount of silica it contains. The first minerals to melt are those with
 
  What will be an ideal response?

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Answer to Question 1

Answer: D

Answer to Question 2

A) lowest melting point and lowest silica content.
B) lowest melting point and highest silica content.
C) lowest silica content and highest melting point.
D) highest silica content and highest melting point.