Question

A drop of olive oil of radius r , spreads into circular film of radius R on the water surface.The molecular size of olive oil is

Consider thickness of film as one molecular diameter

Answer 1

A drop of olive oil of radius r , spreads into circular film of radius R on the water surface.

volume of olive oil drop = volume of sphere = 4/3 πr³

volume of circular film = area of circular film × thickness of this circular film

= πR² × diameter of molecule

[ a/c to question, thickness of film as one molecular diameter]

so, volume of olive oil drop = volume of circular film

or, 4/3 πr³ = πR³ × diameter of molecule

or, diameter of molecule = 4r³/3R³

we know, diameter of molecule denotes size of molecule.

so, molecular size of olive oil = 4r³/3R³