Solving a chemistry problem

2. Using the method of in-line ultramicroscopy, 80 aerosol particles (smoke from open-hearth furnaces) were counted in a volume W=2*10-11 m3. Aerosol concentration C=10-4 kg/m3, density p=2 g/cm3. Determine the specific surface area of particles and dispersion, considering their shape: a) spherical; b) cubic.