Density of a substance is defined as the mass of that substance per unit volume of it.
[tex] Density = \frac{Mass}{Volume} [/tex]
Given the density of Helium = 0.1786[tex] \frac{kg}{m^{3}} [/tex]
Volume of Helium = [tex] 6.28 * 10^{9} mL [/tex]
Converting the volume from mL to [tex] m^{3} [/tex]:
[tex] 6.28*10^{9}mL * \frac{1L}{1000mL}*\frac{1m^{3}}{1000L} = 6280m^{3} [/tex]
Finding mass of Helium from density and volume:
[tex] 6280m^{3}*0.1786\frac{kg}{m^{3}} * \frac{1000g}{1kg} = 1.12 * 10^{6} g [/tex]