Eliza places an 18-gram piece of an unknown substance into a graduated cylinder that is filled with 5 mL of water, and the water rises from the 5 mL line to the 8 mL line. What is the density of the unknown substance in g/mL? A) 3.6 g/mL
B) 8 g/mL
C) 0.167 g/mL
D) 6 g/mL

Which statement is true according to the kinetic theory? a. molecules of different gases with the same mass and temperature always have the same average density. b. molecules of different gases with the same mass and temperature always have the same average volume. c. molecules of different gases with the same mass and temperature always have the same pressure. d. molecules of different gases with the same mass and temperature always have the same molecular mass. e. molecules of different gases with the same mass and temperature always have the same average kinetic energy.