What material of the same weight has the largest volume?

The choice of dry sand as the material with the largest volume for a given weight can be understood by considering the density of the materials involved. Density is defined as mass per unit volume. If we have two materials with the same weight but different densities, the material with the lower density will have a larger volume.

Granite, concrete, and steel are all significantly denser than dry sand. Granite has a density of about 2.7 grams per cubic centimeter, concrete varies around 2.4 grams per cubic centimeter, and steel is typically around 7.8 grams per cubic centimeter. In contrast, dry sand has a much lower density, generally around 1.5 grams per cubic centimeter, which means for the same weight, it occupies a greater volume compared to the other materials.

Therefore, when considering the same weight, dry sand will take up more space than granite, concrete, or steel. This fundamental relationship between density and volume elucidates why dry sand is the correct answer in this context.