'Adsorption' principle is used for which of the following purification method?

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:

What happens when a lyophilic sol is added to a lyophobic sol?

Four gases A, B, C and D have critical temperatures $$5.3,33.2,126.0$$ and $$154.3 \mathrm{~K}$$ respectively. For their adsorption on a fixed amount of charcoal, the correct order is: