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Which statement best explains why an object weight less on mercury than it does on earth

How is coal extracted from mountaintop removal mines? a. dynamite is used to create underground tunnels where miners go to extract the coal. b. dynamite is used to break apart rocks and then draglines are used to remove the broken rock and reach the coal. c. coal in mountaintops is extracted by digging strips in the landscape to reach the coal. d. placer deposits in mountain river bottoms are removed by

If the chemical properties of a substance remain unchanged and appearance or shape of a substance changes it is called a ?