A student measures the mass of a rock to be 20.687 grams. Next, the student fills a graduated cylinder with 15.0 mL of water. When the student adds the rock to the graduated cylinder, the water level rises
to 17.2 mL. What is the density of the rock rounded to three significant figures?

Explain why scientists use shared characteristics to make cladograms.

What amount of heat is exchanged when 106.2 grams of substance y goes from a liquid at 35 degrees celsius to a solid at the same temperature? melting point of substance y = 35 degrees c; δhvaporization = 3.67 j/mol; δhfusion = 3.30 j/mol. mwsubstance y = 28.22 g/mol. −12.4 j −3.51 x 102 j 1.24 x 101 j 351 j

What is the enthalpy of combustion (per mole) of c4h10 (g)? –2,657.5 kj/mol –5315.0 kj/mol –509.7 kj/mol –254.8 kj/mol