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A rock weighing 30.0 g is placed in a graduated cylinder displacing the volume from 22.3 mL to 27.6 mL. what is the density of the rock in grams/cubic centimeter?

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J.R. S. | Ph.D. in Biochemistry--University Professor--Chemistry TutorPh.D. in Biochemistry--University Profes...
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The volume displaced = the volume of the rock.  Look up and read about Archimedes Principle.
Thus, volume of rock = 27.6 ml - 22.3 ml = 5.3 ml.  Also recall that 1 ml = 1cm3
Density = 30.0 g/5.3 cm3 = 5.66 g/cm3 = 5.7G/ cm3
I've reported the answer to 2 significant figures based on subtracting the volumes and using 1 decimal place (5.3 ml has 2 significant figures).