a drop of oil of radius 0-20mm spreads on a circular film of diameter 20mm on the water surface. Estimate the size of molecule.

To estimate the size of the molecule, we need to consider the spreading of the oil drop on the water surface.

The spreading of the oil drop on the water surface can be explained using the concept of surface tension. Surface tension is the property of liquids that allows them to resist an external force, thereby minimizing the surface area. When a drop of oil is placed on water, the oil molecules tend to spread out as much as possible to minimize the surface area.

In this case, the oil drop spreads on the water surface to form a circular film with a diameter of 20mm. The diameter of the circular film is equal to the diameter of the oil drop.

Let's assume that the oil drop forms a perfect circle when it spreads on the water surface. The radius of the circular film is given as 20mm/2 = 10mm.

Now, we can estimate the size of the molecule using the following steps:

1. Calculate the area of the circular film:
Area = π * radius^2
Area = π * (10mm)^2
Area ≈ 314.16 mm^2

2. Estimate the number of molecules in the circular film:
We know that the area of one molecule is very small. Therefore, we can assume that the circular film is made up of closely packed molecules.

If we assume that the circular film consists of a monolayer of molecules, meaning that one molecule thick layer covers the entire area, we can estimate the number of molecules by dividing the area by the area occupied by one molecule.

Let's assume that the area occupied by one molecule is A_molecule.

Number of molecules = Area / A_molecule

3. Calculate the size of one molecule:
Size of one molecule = Diameter of the molecule

So, we can estimate the size of the molecule by knowing the area of the circular film and assuming a monolayer of molecules.

Please note that this estimation assumes ideal conditions and simplifications. In reality, molecular sizes can vary, and the spreading behavior of molecules may not be perfectly uniform.