hello FISMAQUIM,

i think the mean distance in diamond and graphen will be approximately the same but not in fullerene, because of the bulkiness. So fullerene will have the lowest density because less atoms per unit volume.

density from

wiki confirms: graphite 2.3 & diamond 3.5

Now we can calculate the the mass: mass[g] = Volume[cm^3]*density[g/cm^3] and

Volume= (4pi*r^3)/3 where r = diameter/2 = 1cm

so m = (4pi/3)*0.178 ~ 0.2g