[Vadevalor]

When a drop of oil of mass m and density D is put on a water surface it spreads over a circular area of diameter d. assuming this area consists of a monomolecular layer which one of the following gives the approximate diameter of a molecule?
A. m/ (pi D d)
B. D/ (pi d m)
C. 3m/ (4 pi dcube D)
D. 4m/ (pi dsquare D)


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[Stonebridge]

The shape of the oil drop becomes a very thin cylinder when it spreads.
The formula for the volume of a cylinder is cross section area times thickness.
The thickness of this thin cylinder is approximately the molecular diameter you are looking for.
The drop was originally a sphere, for which you know the formula for the volume.

[Vadevalor]

Got it thx!

[Vadevalor]

Got it thx!