What are the requirements in terms of size of particle for scattering take place? Will scattering not take place if the size of a particle is too big or too small ? If yes then what will happen ?

Dear student,
When the size of the scatterer is much greater than the wavelength of incident light, the Rayleigh scattering does not hold true.
As the atmospheric  molecules are small, the Rayleigh scattering law is valid. And
 $$\begin{gathered} I \propto \frac{1}{{\lambda }^4} \\ I = intensity of scatterred light \\ \lambda = wavelength of incident light \end{gathered}$$
This equation only holds for the scattered particles whose dimension is less than the wavelength of visible light. That's the requirement  in terms of size of particle for scattering to take place.
That's why the visible light with least wavelength scattered most and visible light with maximum wavelength scattered least. On the basis of this, we can explain the blue colour of sky.
But in case of cloud, it consists of large dust particles,and comparatively large water droplets, ice particles. This size of the molecules in the cloud is greater than the incident light wavelength, that's why all the components of light are scattered in equal extent. And cloud appears to be white.

Regards,