Which has more mass styrafoam or metal?

Answer 1

mass is sort of like the measure of an objects volume, and has no set number per substance, but density is a fixed figure. As to which object is denser, it depends what type of metal you are talking about, but most of the time metal would be more dense. As to how much mass they have, it depends how big the piece of Styrofoam is, and what type and how big the metal is.

Answer 2

This is not necessarily true. For example a 50g ball of any metal has exactly the same mass as a 50g ball of styrofoam. Metals, however, are far more dense than styrofoam, which is why a metal ball of the same dimensions as a styrofoam ball will have a greater mass.