Which of the following nanomaterials has two dimensions less than $100 \ nm$?

The surface tension of a hydrophilic sol is:

The stability of lyophilic colloids is due to

Consider the following statements related to colloids.
$(I)$ Lyophobic colloids are not formed by simple mixing of dispersed phase and dispersion medium.
$(II)$ For emulsions,both the dispersed phase and the dispersion medium are liquid.
$(III)$ Micelles are produced by dissolving a surfactant in any solvent at any temperature.
$(IV)$ Tyndall effect can be observed from a colloidal solution with dispersed phase having the same refractive index as that of the dispersion medium.
The option with the correct set of statements is

Which of the following processes does $NOT$ result in coagulation?

Which of the following will show Tyndall effect?