Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : The diameter of colloidal particles in solution should not be much smaller than wavelength of light to show Tyndall effect.
Reason R : The light scatters in all directions when the size of particles is large enough.
In the light of the above statements, choose the correct answer from the options given below :

Assertion A: The diameter of colloidal particles should not be much smaller than the wavelength of light to show the Tyndall effect.

This is true. For the Tyndall effect (scattering of light), the particle size must be comparable to the wavelength of light. If particles are much smaller than the wavelength, they won't scatter light effectively.

Reason R: Light scatters in all directions when the size of particles is large enough.

This is true. When particles are of appropriate size, they scatter light in all directions, making the beam visible (Tyndall effect).

R correctly explains why the particle size matters for the Tyndall effect - the scattering occurs when particles are large enough relative to the wavelength.

Both A and R are correct and R is the correct explanation of A.

This matches option 4.