Question

A drop of olive oil of radius 0.25 mm spreads into a circular film of diameter 20cm on the water surface. Estimate the size of the oil molecule.

Answer 1

Correct Answer - `2.08 xx10^(-9) m`
Suppose the film is one molecule thick. If d is
diameter of an oil molecule, then
`d = ("volume of oil drop")/("area of the film") = ((4)/(3)pir^3)/(piR^2) = (4)/(3) (r^3)/(R^2)`
`d = (4)/(3)(0.25xx10^(-3))^3/((0.1)^2) = 2.08xx10^(-9)m`