Five mL of ethanol has a mass of 3.9 g, and 5.0 mL of benzene has a mass of 44 g. Which liquid is denser?

Benzene

Explanation:

A denser substance will have a higher or larger mass in the same volume. Therfore benzene will be a denser liquid as the mass is bigger in the same volume compared to ethonal.

You can also work this out by using the density formula which is mass of the substance over the unit of volume.  

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.