Copper is now extracted from ores containing a low percentage of copper compounds suggest two reasons why?

Ineed ! i have no clue how to do this problem.

Which would freeze at a higher temperature: the great salt lake or lake tahoe? a. lake tahoe would freeze at a higher temperature. b. the great salt lake would freeze at a higher temperature. c. both lakes would freeze at the same temperature.

Which words or phrases identify layers of groundwater? check all that apply. water table kettle lake saturation zone underground lake sinkhole will give brainiest, answer quickly.