Question

What measurements must be known in order to find the density of a substance?

Answer 1

Well, by definition...`rho_"density"="mass"/"volume"`

Explanation:

And so to find the density of some stuff we need a measurement of (i) the mass of the stuff, and (ii) the volume it expresses or the volume to which it is confined (for solids and liquids, the volume is more or less constant; gases, can exhibit varying densities depending on conditions).

And the quotient `rho_"density"="mass"/"volume"` clearly gives us appropriate units of density as `g*mL^-1-=g*cm^-3`, or (for gases), `g*L^-1`.