10. A drop of olive oil of radius 1mm spreads into a circular film of diameter 40 cm on water surface. Estimate the size of an oil molecule.
Let us suppose that olive oil spreads as a film which is one molecule thick on the water surface then the thickness of the film would give an estimate of diameter of the molecule. d= Volume of the oil drop / Area of the film = 4/3πr^3/πr^2 =4/3 *(1/10)^3 *1/400 = 0.33 *10^-5 = 3.3 *10^-6 cm = 3.3 *10^-8 m