What property of an object can you determine using mass and volume

Density,density=mass/volume
density is the mass per unit volume of an object of  which has the unit of g/m3 or Kg/m3

Because electrons have negligible mass, to account for the mass of the isotope, there must be 16 neutrons, 16 neutrally charged, massive, fundamental particles present in the sulfur nucleus. and thus finally, if we have the 32s2− ion, there are 18 electrons, 16 protons, and 16 neutrons.