Have you ever looked up the density of a substance ? You ought to try it. Go ahead. Pick a substance, then go online or open up an actual book and find its density. You will never see any particular volume mentioned along with the density . . . because it doesn't matter. The whole idea of density is that it describes the substance, no matter how much or how little you have of it. The density of a tiny drop of water under a microscope is the same as the density of a supertanker-ful of water.
The density stays the same because it's all one substance
Increasing the amount of a substance does not change its density because density is an intensive property. Regardless of how much of the substance you have, its density remains constant at a given temperature and pressure. For instance, both 1 liter and 10 liters of water have a density of about 1 g/mL.
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