Suppose you have taken a dilute solution of oleic acid in such a way that its concentration becomes $0.01 \mathrm{~cm}^{3}$ of oleic acid per $\mathrm{cm}^{3}$ of the solution. Then you make a thin film of this
solution (monomolecular thickness) of area $4 \mathrm{~cm}^{2}$ by considering 100
spherical drops of radius $\left(\frac{3}{40 \pi}\right)^{\frac{1}{3}} \times 10^{-3} \mathrm{~cm}$. Then the thickness of oleic acid layer will be $x \times 10^{-14} \mathrm{~m}$.
Where $\mathrm{x}$ is
(25)
$4 \mathrm{t}_{\mathrm{T}}=100 \times \frac{4}{3} \pi \mathrm{r}^{3}$
$=100 \times \frac{4 \pi}{3} \times \frac{3}{40 \pi} \times 10^{-9}=10^{-8} \mathrm{~cm}^{3}$
$\mathrm{t}_{\mathrm{T}}=25 \times 10^{-10} \mathrm{~cm}$
$=25 \times 10^{-12} \mathrm{~m}$
$\mathrm{t}_{0}=0.01 \mathrm{t}_{\mathrm{T}}=25 \times 10^{-14} \mathrm{~m}$
$=25$