Among objects of the same size, which is considered the lightest?

The lightest among objects of the same size is dry sand, due to its relatively low density compared to granite, lead, and clay. Density is defined as mass per unit volume, so when objects are of equal size, the one with the lowest density will weigh the least.

Granite is a dense rock, known for its strength and weight. Lead is a metal with a very high density, making it significantly heavier than the other materials listed. Clay, while less dense than granite and lead, is generally heavier than dry sand. Dry sand has air spaces between the grains, reducing its overall density, which is why it is the lightest choice among these options when comparing equal volumes.