If you were given equal volumes of Styrofoam and lead, how would their masses compare? How would their densities therefore compare?

The mass of lead would be significantly greater than the mass of Styrofoam because lead is much denser than Styrofoam. Lead has a density of 11,340 kg/m^3, while Styrofoam has a density of only about 75 kg/m^3. Therefore, the mass of lead would be much greater than the mass of Styrofoam for equal volumes of the two materials.