The atom's radius and mass increase from top to bottom. The density of elements from top to bottom also increases in a periodic table.
Density of Sn= Mass of Sn/Volume of Sn
=24.3968/7.28
=3.49 g/ml*ml/cm³
=3.49 g/cm³
It is accurate to assume that the density of Sn will fall between that of Si and lead . the mass number and radius of the atoms increase from group to group as we move from top to bottom in a periodic table.. The density rises because the increase in mass number is greater than the increase in radius. Simply multiplying by the molar mass of the gas allows one to derive the formula for mass density from the formula for number density. Do not forget that the mass is equal to the moles (n) times the molar mass (M). Smaller masses can be measured in grams instead of kilograms (kg), which is the standard SI unit for mass.
I'd go for D here. It also fits in with the idea of thermal expansion - as something is heated up, molecules vibrate and maybe collide. they vibrate with bigger amplitudes, so taking up more space, so expanding. maybe
