The conditions given below are in the context of observing Tyndall effect in colloidal solutions 

A:The diameter of the colloidal particles is comparable to the wavelength of light used

B: The diameter of the colloidal particles in much smaller than the wavelength of light used

C: The diameter of the colloidal particles is much larger than the wavelength of light used

D: The refractive indices of the dispersed phase and the dispersion medium are comparable

E: The dispersed phase is a very different refractive index from the dispersion .

Number of correct statements in the above list is_______.

The phenomenon of scattering of light by colloidal particles as a result of which the path of the beam becomes visible is called a tyndall effect.Read more on Sarthaks.com - https://www.sarthaks.com/1174037/the-conditions-given-below-are-the-context-observing-tyndall-effect-colloidal-solutions

There are certain conditions needed for the Tyndall Effect such as:

(1).The diameter of the dispersed particles is comparable to the wavelength of the light.

(2) The refractive indexes of both dispersed phase and dispersed medium must differ by large in magnitude.

Thus the correct option is A and E.

Hence the Number of correct statements in the above list is $2$.