A solid compound has a mass of 24.32 g. You scrape 4.5 g worth of material off the compound for testing. What percentage of the compound is leftover? 14. While cleaning your attic, you found your old rock collection. If 74.2% of the rocks have a mass of 5.8 g, and the rest a mass of 6.3 g, what is the average rock mass of your collection? 15. You have 50 mL of water in a graduated cylinder. After dropping a pebble into the graduated cylinder, it now reads 56 mL. What is the volume of the pebble?