143. Solving a chemistry problem

3.5. For the Al2O3 hydrosol, calculate the height at which the particle concentration decreases 2.7 times. The particle shape is spherical, the specific surface of the dispersed phase of the hydrosol: a) 109 m – 1;
b) 0.5 * 10 ^ 9 m – 1; c) 108 m – 1. The density of Al2O3 is 4 g / cm3, the density of the dispersion medium is 1 g / cm3, and the temperature is 293 K.