)1/3×10−3cm The volume of 100 spherical drops, V=100×
4πr3
3
Substituting the value of the radius in the above equation, we get V=100×
4π
3
×
3
40π
×10−9 V=10−8cm3 Now, Volume of the film = Area of the film × Thickness of the film ⇒ Volume of the film =4×t The film is made up of 100 spherical drops. ∴ The volume of the film = Volume of 100 spherical drops 4t=10−8⇒t=25×10−12m The thickness of the oleic layer, t0=0.01×t=25×10−14m Comparing with x×10−14, we get x=25