122. Solving a chemistry problem

The silica sol was studied by osmometry at 25.0 °C with the following results:

c*, g/l 80 60 40 20 10 5
п, Pa 252.2 110.8 64.5 20.3 9.23 4
*с – grams of SiO2 per liter of solution.
Assuming sol particles to be spherical and monodisperse, determine the molar mass of the particles, the number of SiO2 formula units in one particle, the radius of the particles, and the specific surface area. The silica density in this ash is 2.0 g/cm3.